Democrats in Congress who passed historic legislation on Sunday to revamp the US health care system face a new challenge over the next seven months: convincing voters it's a good deal. If Democrat lawmakers fail to counter public opposition, it could cost them their jobs in mid-term elections in November, return control of Congress to Republicans and weaken Democratic President Barack Obama halfway into his first term. How the high-stakes battle shakes out – if it hurts or helps Democrats or Republicans – is a mystery, even to Obama. “I don't know how health care reform will play politically, but I know it is the right thing to do,” he said at a campaign-style rally near Washington on Friday. The sluggish US economy, with 9.7 percent unemployment, promises to be the key factor in November elections for Congress. But health care will loom large. Democrats and Republicans – along with labor, business and other special interests – waged a multimillion-dollar TV advertising war and intend to finance more in weeks to come, many aimed at specific lawmakers who voted “yes” or “no.” Opinion polls show the public, by a margin of 49 percent to 40 percent, opposed the legislation which Republicans denounced as a costly and misguided federal takeover of health care. Democrats rejected the complaints and contended that public support would grow once more was known about the overhaul which will provide coverage to millions of uninsured Americans and is projected to reduce the federal deficit. Key elements this year As part of their strategy, Democrats intend to highlight key elements set to take effect this year. They include providing tax credits to small businesses to purchase insurance for employees; stopping insurance companies from dropping people with pre-existing conditions; increasing funding for community health centers and permitting those up to age 26 to be on their parents' health insurance policies. “This is going to be a political winner,” said Brad Woodhouse, a Democratic Party spokesman. “Republican myths about the bill won't withstand reality.” Republicans defend their criticism and warn Democrats that they will be targeted for defeat on Election Day, Nov. 2, when all 435 seats in the House of Representatives and about a third of the 100 seats in the Senate will be up for grabs. “It will be the issue in every race in America,” promised Senate Republican Leader Mitch McConnell. Democratic Representative John Boccieri, who as a member of the Air Force Reserves flew cargo planes in Iraq before being elected to Congress in 2008, brushes off such talk. “It's no more pressure than flying missions out of Baghdad,” Boccieri said on Friday after he switched and announced his support of the health care reform bill. At least 36 states, most with Republican governors, have moved to limit or oppose provisions of the legislation, including a requirement that nearly everyone buy health insurance. “There's going to be a big free-for-all lawsuit about this,” said Michael Bird, legislative counsel for the National Conference of State Legislatures. Court fight On Capitol Hill, Democrats voice confidence that federal law will prevail over state law. But election-year court fights would open Democrats to complaints of bullying the states. Before the health care overhaul was brought up for final passage, Club for Growth, a conservative group, began a campaign to repeal it. As of Sunday, 37 Republican US lawmakers and more than 160 Republican congressional candidates were listed as having signed a pledge to back the effort. White House adviser David Axelrod dared Republicans to push for repeal, saying they would have to defend allowing insurance companies to deny coverage to sick people. Chris Krueger of Concept Capital, a private firm that tracks Congress for institutional investors, said Democrats were in a bind. “I wouldn't want to be in a position where I hope public opinion shifts. It's going to be tough,” Krueger said. Patrick Caddell and Douglas Schoen, pollsters for the previous two Democratic presidents, Jimmy Carter and Bill Clinton, respectively, view the party as in trouble. In The Washington Post this month, they wrote: “Unless the Democrats fundamentally change their approach, they will produce not just a march of folly but also run the risk of unmitigated disaster in November.” Responding to Cadell and Schoen in The Huffington Post, pollster John Zogby noted Republicans face problems with voters on health care as well. Zogby said when asked which party put the nation ahead of politics in the health care debate, most independents and almost half of Republicans, chose Democrats.