They were cajoled in the Oval Office and called from Air Force One. Interest-group attack ads saturated television in their districts, and their office phones never stopped ringing.

Undecided House Democrats found themselves in a political maelstrom the last few weeks as the vote on legislation to remake the health-care system neared.

Sunday night's House approval along party lines doesn't mean the pressure is off those Democrats, however.

Rep. John Larson of Connecticut, chairman of the House Democratic caucus, said it was "quite possible" that some would lose their seats in the Nov. 2 midterm election for control of Congress. "You risk the chance," he said.

Most vulnerable: Democrats from conservative-leaning districts who had fiscal concerns or wanted assurances that the government would not subsidize abortion coverage, many of whom waited until the last minute to decide. They include Rep. John Adler of New Jersey and at least six Pennsylvania representatives.

Adler and two of those six, Jason Altmire and Tim Holden, voted no; the four other Pennsylvanians - Chris Carney, Kathleen Dahlkemper, Paul Kanjorski, and Patrick Murphy - voted yes.

Health care is bound to shape the midterm election, with Republicans already vowing repeal and Democrats hoping that the farthest-reaching domestic legislation in nearly 50 years would provide a jolt of energy to their dispirited base voters.

It remains to be seen, analysts say, whether the historic passage will cause more harm to the Democrats - or help them turn around their fortunes before November. Already, the nasty 14-month debate over the legislation has damaged President Obama and his party, inspiring the grassroots "tea party" movement and allegations that Obama is seeking a "government takeover" of health care.

As the process dragged on, Obama's approval rating in some recent polls slid below 50 percent. With their majorities in the House and Senate hanging in the balance, Democrats fear substantial losses in the fall. After all, the party in control of the White House almost always loses congressional seats in the midterm election, and the issue has fired up Republican voters.

Adler, a first-term lawmaker whose South Jersey district had been held by Republicans for more than a century, also voted against the initial House health-care bill in November.

In both cases, he said, the bills did nothing to control the system's underlying problem: ever-increasing costs.

"Congress needs to do . . . the cost side right now in addition to the coverage side, or you'll see a lot of folks not have jobs," Adler said.

He met with Obama in the Oval Office last week for what he called a "respectful" discussion of his objections.

Carney, who represents northeastern Pennsylvania's 10th District, voted yes after agonizing over the abortion issue. He was among the small group of lawmakers who met with White House officials Saturday and Sunday to structure a deal for an executive order reinforcing the long-standing federal ban on funding for abortion.

That agreement won the votes of a number of antiabortion Democrats.

Carney had voted for the initial House version of the legislation, which contained stricter language on abortion funding than the Senate version approved yesterday.

More than a half-dozen interest groups spent in excess of $500,000 to run ads in the Scranton/Wilkes-Barre television market.

Carney on Sunday noted Obama's promised executive order and the requirement in the health legislation that insurers cover maternity care. "This bill is about life," he said during a Capitol Hill news conference.

Dahlkemper, a first-term Democrat from Erie's Third District, was also one of the abortion holdouts who voted in favor of the bill.

The House approved the health-care bill that had already cleared the Senate, then moved to pass a companion measure with changes. The Senate still must pass those changes and Obama must sign the legislation for the overhaul to become law.

Assuming that happens, Democrats will face the task of convincing the public over the next eight months that the health-care measure is better than polls suggest Americans think it is.

Complicating that task: Some of the measure's most popular provisions would not take full effect until 2014. But a tax increase on unearned income and changes to Medicare designed to help pay for the plan would begin as soon as next year.

"It's not going to be popular by November," Sen. Claire McCaskill (D., Mo.) told Politico last week. "It'll be popular 10 years from now."

Party strategists plan to highlight popular benefits that would take effect immediately, including requiring insurance companies to cover children with preexisting conditions and reducing co-payments by seniors who get prescription drugs through Medicare.

"Failure would have been a political disaster," said Daniel F. McElhatton, a Democratic strategist and partner in the Echo Group of Philadelphia. "The base is already depressed. Now, this could reactivate the young voters, minorities, and independents who elected Obama."

Republicans won governorships in New Jersey and Virginia late last year and a special Senate election in Massachusetts in January in large part because the "surge" Obama voters who showed up in 2008 stayed home.

While a Wall Street Journal/NBC News poll released last week found mixed opinions on the health-care legislation overall, core Democratic voters surveyed strongly supported it.

And several polls have indicated there's an "enthusiasm gap" between the parties, with more Republican voters expressing intense interest in the November election. The measurement is often used to project which party is likely to have higher turnout.

"Health care is the key defining issue for Democrats in swing districts who voted for it," said Jordan Sekulow, a GOP strategist who worked on the campaigns of Mitt Romney and former President George W. Bush. "Those who voted against it - it may be the way that they are saved."

For Republicans, passage of the health-care legislation "was the rallying cry the party needed," he said. Since 2006, when Democrats recaptured the House, the "energy has been sucked out of the party," Sekulow said.

Murphy, who represents Bucks County, provided a preview of the Democrats' pitch Sunday as he addressed 100 people at an Organizing for America rally in Langhorne to thank him for supporting the bill.

"Today is the beginning of this fight and not the end," Murphy told the gathering by phone. "The special-interest groups are already lining up to take power and repeal it."

Larry Sabato, political scientist at the University of Virginia, said the delay in when the bill's full features take effect could lead opponents to soften and supporters to be disappointed. " 'They promised me the sun, the moon, and the stars, and I haven't even seen fairy dust,' " Sabato said.

He said he believed both parties were optimistic in their assessments of how the issue would play in November.

"The Democrats are not going to convince a lot of people that it's a great bill after the fact, and the Republicans are going to have trouble sustaining enthusiasm for the years it would take to repeal it," Sabato said.

Social Security and Medicare inspired GOP opposition and vows of repeal when they passed, and both programs became part of America's social fabric. On the other hand, both had bipartisan support.