Passengers fill up Washington Metro subway cars in Arlington, Va., Thursday, Oct. 17, 2013 as workers return to their jobs after a budget fight on Capitol Hill that resulted in a partial government shutdown is resolved. An audience comprising of White House staff members, stands as President Barack Obama leaves the State Dining Room of the White House in Washington, Thursday, Oct. 17, 2013, after he made a statement. WASHINGTON (AP) - In withering day-after criticism, President Barack Obama declared Thursday that the 16-day partial government shutdown was a Republican-provoked spectacle that "encouraged our enemies" around the world. Elsewhere in Washington, and around the country, federal employees simply streamed back to their jobs. National parks reopened. The popular panda cam at the National Zoo came back online. But there was no letup in the political fight. Fresh from a defeat, tea party groups and their allies renewed fundraising efforts with a promise of future assaults on Obama's health care overhaul - and a threat of more election primaries against Republican incumbents who don't stand with them. Government spending was still front and center. Inside the Capitol, lawmakers charged with forging a post-shutdown deficit-cutting agreement in the next 60 days met privately. "We believe there is common ground," said Sen. Patty Murray, D-Wash., chair of the Senate Budget Committee. Privately, however, officials in both parties said the prospects for a major breakthrough were dim, given differences over taxes and spending that have proven compromise-proof throughout the current three-year era of divided government. A few hours after Obama placed his post-midnight signature on legislation ending the long political showdown, Vice President Joe Biden was at the Environmental Protection Agency to greet returning employees. "I hope this is the end of this," he said, but he acknowledged "There's no guarantees." That was a reference to the last-minute legislation that will fund the government only until Jan 15 and give Treasury the ability to borrow above the $16.7 trillion limit until Feb. 7 or a few weeks longer. At the White House, Obama blended sharp criticism of Republicans with a plea for their cooperation over the remainder of the year and a call for less shrillness on both sides. "Some of the same folks who pushed for the shutdown and threatened default claimed their actions were needed to get America back on track," he said in remarks in the State Dining Room. But probably nothing has done more damage to America's credibility to the world. ... It's encouraged our enemies. It's emboldened our competitors. And it's depressed our friends who look to us for steady leadership," he said. Obama said the public is "completely fed up with Washington" and he and Congress face hard work in regaining trust. It was a reference to public opinion polls that show the nation in a sour mood - though more inclined to blame Republicans than the president and his party for the first partial government shutdown caused by politics in 17 years. Hoping to jump-start his own stalled agenda, Obama urged lawmakers to concentrate on three items in the coming weeks: a balanced plan to reduce long-term deficits, legislation to overhaul the immigration system and passage of a farm bill. Polling aside, Obama's party emerged from the three-week showdown in Congress united. All Democrats in Congress supported the legislation that passed Wednesday night to fund the government and raise the debt limit. Not so of the Republicans. Eighteen GOP members in the Senate and 144 in the House opposed the legislation, while 27 in the Senate and 87 in the House supported it. The fault line separated tea party adherents from the balance of the rank and file. And there were clear signs the split was enduring, though not widening. In Mississippi, where GOP Sen. Thad Cochran has not yet announced if he will seek a new term in 2014, the Club for Growth and Senate Conservatives Fund were not waiting to find out. They endorsed a potential rival, Republican state Sen. Chris McDaniel, as he announced his candidacy. The groups are among several that have played an increasingly active role in Republican primary elections in recent years, several times supporting tea party-aligned challengers. In some cases - Sen. Ted Cruz of Texas, for one - they went on to victory in the fall. In more, they lost seemingly winnable races to Democrats. One survivor of such a challenge, Sen. Orrin Hatch, R-Utah, said during the day that the Heritage Foundation is in danger of losing its clout as a reliable conservative think tank because of the actions of its political arm, Heritage Action. In an interview on MSNBC, he said, "There's a real question in the minds of many Republicans now. ... Is Heritage going to go so political that it really doesn't amount to anything anymore? Heritage Action played an influential role in the two-week political showdown. In the days leading to the impasse, it was a strong backer of the campaign to demand that "Obamacare" be defunded in exchange for Republican approval of funding for the government. And on Tuesday, as it was hosting a fundraiser at a high-end golf resort in Bandon, Ore., the group weighed in to oppose legislation that House Speaker John Boehner put together in hopes of retaining influence in the final negotiations over the impasse in Washington. Yet another group, Americans for Limited Government, assailed Rep. Scott Rigell, R-Va., who voted for the legislation that reopened the government and raised the debt limit. Noting that the measure had not defunded the health care law, the group said the congressman "owns Obamacare just as much as if it had been a vote to adopt it in the first place." In a statement issued on Wednesday in connection with his vote, Rigell said he was voting for the bill "given the lack of a viable alternative at this moment." Other Republicans have said for weeks that the strategy of demanding Obama kill off the health care law he won from Congress never had a chance of success. "This was a terrible idea," Sen. John McCain of Arizona said on CNN of the shutdown. He said it will not happen again when the next deadlines arrive - "I guarantee it." But in a party divided, there were dissenters. "Obamacare is still fully intact, out-of-control spending continues, the debt limit is raised without addressing unsustainable spending, and only vague promises are left to address these key issues," the Tea Party Express said in an online fundraising appeal. Referring to next year's elections, the group said, "To put it plain and simple: We don't have enough conservatives in Congress to stop the irresponsible spending in Washington." Spending will be the focus for the high-level budget negotiators who began their new assignment Thursday. "Talking doesn't guarantee success," said Rep. Chris Van Hollen of Maryland, senior Democrat on the House Budget Committee, after he met with Democratic Sen. Murray, Republican House Budget Chairman Paul Ryan of Wisconsin and Alabama Sen. Jeff Sessions, senior Republican on the Senate committee. But, Van Hollen added, "if you don't get together, obviously you don't move forward." Associated Press writer Alan Fram contributed to this story.