Editor 's note : Julian E. Zelizer is a professor of history and public affairs at Princeton University 's Woodrow Wilson School . His new book , `` Arsenal of Democracy : The Politics of National Security -- From World War II to the War on Terrorism , '' will be published this fall by Basic Books . Zelizer writes widely about current events . Julian Zelizer says some of President Obama 's political vulnerabilities have started to emerge . PRINCETON , New Jersey ( CNN ) -- June has been rough for President Obama . After experiencing enormous success during his first months in office , some of his political vulnerabilities have started to emerge . As Republicans begin to think about the 2010 midterm elections and moderate Democrats decide how they should vote on Obama 's most ambitious initiative , health care , the White House must prevent these weaknesses from becoming debilitating . The first vulnerability is the tension between the left and center of the Democratic Party . Since his election , President Obama has struggled to navigate the divisions that exist between the liberal base of the party , who were the core of his early support , and moderate Democrats , who were also instrumental to his victory . At first , the administration relied on good will and political capital from the election to overcome conflicts , such as when Obama agreed to reductions in the size of the economic stimulus package to placate the conservative Democrats and some Republicans despite the objection of progressives . But the tensions are becoming more pronounced and more difficult to resolve . The president has disappointed gay rights activists for not fulfilling promises they thought he had made on the issue of gay rights . Last week , they expressed their frustration with the Department of Justice 's legal brief supporting the Defense of Marriage Act , a law that prohibits same-sex partners from receiving marriage benefits and protects states that do n't recognize same-sex marriages . Obama failed to calm the storm even when he extended some employment benefits to the same-sex partners of federal workers . He came under fire for having declined to provide health care and retirement benefits on the grounds that such a move would violate the Defense of Marriage Act . These kinds of left-center tensions will intensify when Congress delves into the final negotiations over health care this summer . Progressive Democrats insist that without a public insurance option health care reform will fail in the long run . Several Democratic moderates have been pushing alternatives that fall far short of that goal . The second vulnerability is the deficit . When Republicans have turned away from cultural issues and toward economics , they have been finding more success at attracting the interest of independents and moderates . Recent polls have shown that the public is concerned about the growing size of the deficit and Republicans have finally gained a bit of political traction by linking Obama 's policies to the government 's red ink . To be sure , this is not a home run issue for the GOP . Many commentators have pointed to the hypocrisy of Republicans making anti-deficit arguments following the tax-cutting and spending spree that took place under President Bush . Moreover , deficits have a poor track record in terms of being a winning campaign issue . There have not been any presidential candidates or major midterm elections in recent history that hinged on anti-deficit arguments . Many presidents , including Franklin D. Roosevelt , survived while growing the deficit . Polls have shown the public is also notoriously fickle about how much weight it gives to the deficit as an issue , and is often misinformed about the actual size of the deficit . Nonetheless , warning about rising deficits has been an effective tool for weakening the political strength of an incumbent administration . Regardless of the economics of the issue , with some respected economists saying short-term deficits do n't matter , many Americans perceive the budget deficit as a symbol for whether a president is keeping federal spending under control . While Republicans might not take back Congress by focusing on the deficit , they can erode Obama 's political standing and make it more difficult for him to pass legislation . Finally , there is the economy . The irony for Obama is that as the economy has stabilized , it has become a greater source of political danger . Without an immediate crisis , voters are not as panicked and do n't feel as desperate for federal assistance . A growing number are more comfortable criticizing the administration 's economic policies . Some Republicans have picked up on this and have asked why the U.S. needs to spend the stimulus money if the recession is almost over . At the same time , Obama is in a double bind : Most experts agree that we will have a fragile economy in the foreseeable future , so voters wo n't be happy either . If there is any new dip in the economy , the public will blame President Obama rather than President Bush . This is exactly what happened with the recession in 1937 , which FDR 's opponents called the `` Roosevelt Recession , '' using the downturn to diminish the number of New Deal liberals in the House and Senate in 1938 . Does this mean Obama is finished ? Not at all . The same polls that reveal vulnerabilities show that Obama is still extremely popular with the public and most evidence suggests that he has good standing with congressional Democrats . But in recent weeks a candidate who was once seen as invincible is now seen as potentially vulnerable . This is when the sharks start to circle in American politics . The revelation of weakness gives Republicans , as well as unhappy Democrats , more confidence to challenge the White House . This is not what the president wanted right as he is trying to win support for his health care proposal and the rest of his budget . If the problems are not contained , they can also become the foundation for the Republican campaign for Congress in 2010 . The opinions expressed in this commentary are solely those of Julian Zelizer .
Jim Barnes : June has been a difficult month for President Obama . He says divisions have grown among Democrats on gay rights , health care . Zelizer says growing concerns about deficit could blunt Obama 's campaign . He says a new dip in the budget would be blamed on Obama , not Bush .