WASHINGTON – The House of Representatives on Saturday passed, by a 220-215 vote, health care overhaul legislation that would require virtually all Americans to obtain health insurance and create a government-run insurance plan to help them do so.

If passed by the Senate, the bill would bring about the most sweeping changes in the U.S. health care system since Medicare was created 44 years ago.

Supporters of the measure burst into cheers and applause on the House floor as it became clear the measure had won, but the vote was excruciatingly close, just two more than the bare minimum needed. One Republican, Anh Cao of Louisiana, voted for the bill; 39 Democrats voted against.

President Barack Obama made a personal plea for passage before the all-day debate began.

“Now is the time to finish the job,” Obama said in the White House Rose Garden after meeting with House Democrats.

The job is far from finished. The Senate hopes to act by the end of the year, and if successful, the two bodies would then craft a compromise that would need approval of each chamber.

The House vote came with a warning: Getting enough votes later this year or early in 2010 will not be easy. Thirty-nine Democrats, most from conservative districts or freshmen who narrowly won their 2008 elections, voted against the House bill, joining 176 Republicans. In the Senate, eight to 12 moderates have expressed reservations about that chamber’s proposal.

In addition to creating the so-called public option government-run insurance program, the House bill would bar insurers from denying people coverage because of pre-existing conditions and set up health care “exchanges,” or marketplaces, where consumers could easily shop for coverage.

The changes are expected to mean that by 2019, 96 percent of eligible Americans would have health insurance, up from the current 83 percent.

During his half-hour appearance Saturday on Capitol Hill, Obama took no questions from lawmakers, but his presence was a vivid reminder that the president has put health care overhaul at the top of his domestic agenda – a change that has eluded presidents for nearly a century.

“He came here to say, ‘This is what we said we would do in the campaign. Let’s do it,’” said House Majority Leader Steny Hoyer, D-Md.

On the House floor, Democratic leaders appealed to members’ sense of history, reminding them that this was one of the most significant votes, short of war, that they were likely to take.

Republicans countered with arguments that the health care plan did little to improve coverage or affordability.

“Astoundingly, Democrats are bringing to the floor a bill today that will not reduce the costs of health insurance, it will grow the size of government,” said GOP Conference Chairman Mike Pence of Indiana.

Democratic leaders said they doubted Obama changed many votes, but “the energy he brought to this debate will be helpful,” said Majority Whip Jim Clyburn of South Carolina.

A bigger boost may have come from a deal to bar coverage by government-subsidized insurance policies of elective abortions.

As originally written, the measure would have required insurers to separate public and private money, so that only private funds could be used for elective abortions.

After tense negotiations Friday night – with White House officials and representatives of the U.S. Conference of Catholic Bishops as well as key Democratic members of Congress – House Democratic leaders agreed to allow a vote Saturday on sweeping changes to the abortion provision.

The measure was approved, 240-194, as 64 Democrats joined 176 Republicans to back the change.

The change would permit abortion coverage for people receiving federal aid for their insurance only in the case of rape or incest or when the mother’s life is endangered.

That change is consistent with a 1970s-era federal law governing public funding of abortion.

Under the new provision, only people buying private insurance with their own funds would have an elective abortion covered.