ST. PETERSBURG, Russia — After two days of intense lobbying, President Obama left a summit with world leaders Friday with some expressions of support for a strong U.S. response to Syria's alleged use of chemical weapons, but well short of an international coalition that might help persuade reluctant lawmakers. 
 
 The president had hoped to use the meeting of the Group of 20 nations to build pressure on Congress as it considers whether to authorize missile strikes against Syrian President Bashar Assad's government. 
 
 Before leaving for Washington, Obama said at a news conference that he will make his case in an address from the White House on Tuesday, an acknowledgment that his plans remain divisive both abroad and at home. 
 
 "This is not something that I think a lot of folks around the world, you know, find an appetizing set of choices," he said. "But the question is, do these norms mean something? And if we're not acting, what does that say?" 
 
 The president had to settle for a carefully worded statement backed by representatives of 10 countries that said Assad should be held accountable for an alleged nerve gas attack on the Damascus suburbs two weeks ago, but did not explicitly support military action or promise participation. Among the leaders who did not endorse the statement was the summit's host, Russian President Vladimir Putin, who is Assad's closest ally. 
 
 Obama and Putin pulled up two chairs in a corner and talked for more than 20 minutes Friday, almost entirely about Syria. The leaders have exchanged harsh words, but Putin called the talk "friendly" and Obama said it was "candid and constructive." But it did not break their impasse over how to respond to the suspected chemical weapons attack or how to end the 21/2-year-old Syrian civil war. 
 
 "We both remained unconvinced by each other's opinion," Putin said at a news conference. "But there is a dialogue. We hear each other, we understand arguments, but we don't agree with them." 
 
 Putin added that Russia will continue to supply weapons to Assad in his battle against the rebel opposition. Local news reports said three Russian ships and possibly a fourth were headed to the eastern Mediterranean, where the United States has four guided missile destroyers and an amphibious ship with 300 Marines. 
 
 At a dinner that stretched into morning hours Friday, world leaders vigorously debated Obama's plan, with many saying the president should wait for the United Nations to complete a report on the Aug. 21 attack and sanction a response. Obama argued that the U.N. Security Council was paralyzed by disagreement. Russia and China, which have veto power, have blocked efforts at the Security Council to put pressure on Assad. 
 
 Obama's plan for what he stresses will be "limited and not open-ended" strikes also remains unpopular in the United States. The statement and the heated discussion was a reminder of what Obama has called "a heavy lift" as he seeks to sell lawmakers and the American public on the need for a military response. 
 
 Jon B. Alterman, the director of the Middle East Program at the Center for Strategic and International Studies, said the problem for Obama isn't whether he has international support but American support. "The people who matter right now are Americans," he said. "If he can't convince them, it's catastrophic for his presidency." 
 
 The Senate could take the first vote on the issue as soon as Wednesday, but the House should "expect a robust debate" and a vote in the "next two weeks," Majority Leader Eric Cantor (R-Va.) said. 
 
 Although the Senate Foreign Relations Committee quickly approved a resolution this week, the already challenging politics have since become more complicated. Sen. Joe Manchin III (D-W.Va.), who opposes the resolution, was consulting his colleagues on a proposal for a nonmilitary response. 
 
 In the House, Rep. Chris Van Hollen (D-Md.) said the Senate resolution, which aims to shift the momentum in the civil war toward the opposition, "opens up a Pandora's box." "I think the administration runs an incredible risk, if they try to placate those who want to expand American military intervention in Syria, because they risk losing support of the overwhelming majority of members," he said after meeting with Vice President Joe Biden. 
 
 The Obama administration had resisted intervention in the war, but switched course after the alleged chemical weapons attack, which U.S. intelligence agencies have concluded killed more than 1,400 people. 
 
 On Friday, Obama compared his bid for action to humanitarian intervention in Kosovo in 1999 and the U.S. failure to stop the genocide in Rwanda in 1994. He cast the international division as the result of war-weary leaders "rationalizing not making tough choices." The United States alone, he said, shoulders the burden of enforcing international agreements on human rights and chemical warfare. 
 
 "There are times where we have to make hard choices if we're going to stand up for the things that we care about. And I believe that this is one of those times," Obama said. 
 
 But Obama did not persuade a single ally to endorse a specific action. Immediately after he spoke, the White House released the joint statement from Australia, Britain, Canada, France, Italy, Japan, South Korea, Saudi Arabia, Spain and Turkey, as well as the United States. It found that evidence "clearly points" to Assad's government as responsible for the attack, called for a "strong international response to this grave violation of the world's rules and conscience" and asserted that "the world cannot wait for endless failed processes." 
 
 The statement did not specifically endorse military action, but concluded, "We support efforts undertaken by the United States and other countries to reinforce the prohibition on the use of chemical weapons." 
 
 A White House official, however, said there was no question what that implied. "The president has been very clear about how he intends to do that with tailored military action," a senior administration official said. 
 
 Still, the support was largely symbolic. The British Parliament has voted against participation in a military campaign. French President Francois Hollande, who offered the earliest support for Obama's plan, said Friday that his country will not engage in any action until after U.N. inspectors issue their report on the attack. 
 
 Obama's last-minute decision to ask Congress to vote to approve the use of force gave world leaders little reason to risk supporting a mission that may not occur. The president has insisted that he does not need congressional authorization, but reiterated Friday that it would make a U.S. response "more effective and stronger." 
 
 Obama would not say whether he will launch missiles even if he loses the vote. Pressed on the issue, Obama was blunt. "You're not getting a direct response," he said. "I'm not going to engage in parlor games." 
 
 In his absence from Washington on Friday, Biden, Secretary of State John F. Kerry and Chief of Staff Denis McDonough worked the phones; U.S. officials briefed members of Congress; and Samantha Power, the U.S. ambassador to the United Nations, gave a speech at a think tank, arguing, "The use of limited military force can strengthen our diplomacy and energize the efforts by the U.N. and others." 
 
 When Obama returns to Washington, he will oversee one of the most momentous lobbying efforts in his tenure. He promised that his administration would "systematically" reach out to every member of Congress. 
 
 "I do consider it part of my job to help make the case and to explain to the American people exactly why I think this is the right thing to do," he said, acknowledging that "it's conceivable that, at the end of the day, I don't persuade a majority of the American people that it's the right thing to do." 
 
 kathleen.hennessey@latimes.com 
 
 sergei.loiko@latimes.com 
 
 Hennessey reported from St. Petersburg and Loiko from Moscow. Times staff writers Michael A. Memoli, Christi Parsons and Paul Richter in Washington contributed to this report. ||||| The president's White House speech played it safe, doing little to answer the concerns of doves who oppose the war and hawks who find his plan too small to matter. 
 
 Reuters 
 
 With public opinion on Syria ebbing away from him, President Obama seemingly had two choices for his address to the nation Tuesday night: He could deliver a newly impassioned and emotional version of his case that limited military strikes were necessary and effective. Or he could seize on the premise that circumstances had changed and announce a new policy for how to handle them. 
 
 Instead of either, however, Obama chose to play it very safe. 
 
 The president's speech in the White House's East Room was short -- clocking in at a neat 15 minutes -- and offered hardly anything new. As he has for days, Obama argued that while the the civil war in Syria is a tragedy, there was no justification for American intervention until the use of chemical weapons necessitated it. And he praised, if tentatively, the day's major development -- a nascent but fragile agreement involving Russia that would see Syria surrender its chemical weapons and sign an international treaty prohibiting their use. 
 
 He also emphasized that any attack would be very limited in scope. "I will not put American boots on the ground in Syria," he said. "I will not pursue an open-ended action like Iraq or Afghanistan. I will not pursue a prolonged air campaign like Libya or Kosovo. This would be a targeted strike to achieve a clear objective: deterring the use of chemical weapons and degrading Assad's capabilities." 
 
 Much of the speech was structured as a response to common objections to attacking Syria. And it was here that the lack of novel or more developed replies was most striking. A White House address like this is necessarily targeted to all a wide audience, including those who have paid little attention to the Beltway battle over an attack and might be unfamiliar with the debate. Still, with the minimal support he has for a strike collapsing, he seems to be in no position to hit the same notes. 
 
 Nor did he make much of an emotional plea, though he cited the same horrible deaths of children in sarin attacks that Samantha Power and Susan Rice have made in recent days. The president got most fired up, instead, as he closed his remarks. Asking the right to follow through on its commitment to American military force and the left to follow through on it humanitarian ideals, he asked: 
 
 What kind of world will we live in if the United States of America sees a dictator brazenly violate international law with poison gas and we choose to look the other way? ... Terrible things happen across the globe, and it is beyond our means to right every wrong. But when, with modest effort and risk, we can stop children from being gassed to death and thereby make our own children safer over the long run, I believe we should act. That's what makes America different. That's what makes us exceptional. 
 
 Yet despite the FAQ-like format, Obama perhaps left more questions unanswered than he resolved. 
 
 Disappointingly for hawks and liberal interventionists, the president stubbornly insisted he would not seek to topple Bashar al-Assad -- though in a concession to critics who groaned at John Kerry's promise than an attack would be "unbelievably small," Obama said even a limited campaign would get results: "The United States military doesn't do pinpricks. Even a limited strike will send a message to Assad that no other nation can deliver." But the president didn't offer much reassurance to anyone skeptical about the deterrent power of such a strike, nor did he answer the critique that Assad has killed civilians --including, yes, children -- quite effectively with conventional weapons. 
 
 The administration's argument that sarin attacks in a Syrian neighborhood threaten national security has failed to rouse many in Congress. Obama's reply tonight was elaborate, imagining that failure to act would encourage further attacks by other dictators, endanger regional allies, and in the future perhaps result in American soldiers being gassed. He didn't explain why, for example, Saddam Hussein's use of gas in the 1980s and 1990s didn't create a rash of chemical-weapons attacks, and the vague domino effect and indeterminate timeline seem unlikely to convince the many Americans who have turned against intervention after a decade of wars. Obama's circumspection sometimes undermined his own case, as when he pointed out, "The Assad regime does not have the ability to seriously threaten our military." 
 
 If the speech was intended to sum up the case for war against Syria, it seemed mostly to provide the sharpest summation of Obama's central paradox. Though the president seems personally upset by the chemical-weapons attacks, he knows Americans are weary of war and has little apparent appetite for it himself, so he has to play it safe. That means he does things like promise American boots won't be on the ground, and insists Assad can't touch America. 
 
 But those arguments undermine the case for war, too. If Assad can't hurt Americans, why is it a national-security concern? If American attacks will be so limited, will they even really make much difference, either to stop the slaughter or as a future deterrent? And if it's so important to prevent gas attacks that "brazenly violate international law," why is Obama so willing to conduct a punitive strike that seems to most experts to violate international law? 
 
 With the nation watching, Obama had a chance to resolve these contradictions, and he didn't do it -- he didn't even try. Luckily for him, speeches seldom matter. If the diplomatic maneuverings to get Assad to turn over his chemical weapons succeed, this speech will look like a moment of wise caution when the president treaded water rather than making waves. If they fail, however, he will have squandered a chance -- will anyone really heed his second White House speech on Syria, should he have to make one?
– President Obama didn't exactly return from the G20 summit with a ringing international endorsement to take action against Syria, but he continued making his case before his own nation this morning via his weekly radio address. Obama hit familiar themes, ones he will surely revisit in his speech to the nation Tuesday night, reports Reuters. "This would not be another Iraq or Afghanistan." "Any action we take would be limited, both in time and scope—designed to deter the Syrian government from gassing its own people again and degrade its ability to do so." "I know that the American people are weary after a decade of war, even as the war in Iraq has ended, and the war in Afghanistan is winding down. That's why we're not putting our troops in the middle of somebody else's war." As for the G20 summit: Obama got the backing of 10 countries for a statement that says Bashar al-Assad should be held accountable for using chemical weapons, but the statement pointedly fell short of calling for military action, notes the Los Angeles Times, which concludes that the president "fell well short of an international coalition that might help persuade reluctant lawmakers."