WASHINGTON – The initial blush of President Barack Obama's health care triumph immediately gives way to a sober political reality — he must sell the landmark legislation to an angry and unpredictable electorate, still reeling from the recession.

Voters may not buy it.

And that could mean a disastrous midterm election year for Obama and his fellow Democrats.

"We proved that this government — a government of the people and by the people — still works for the people," the president said late Sunday, beginning his sales pitch from the White House one hour after Congress passed the sweeping measure.

"This isn't radical reform but it is major reform," he added. "This is what change looks like."

Obama and the Democrats are certain to look for a much-needed political lift from the legislation, a capstone for a young presidency and a party after decades of trying to remake the nation's health care system.

But there's no guarantee they'll get it.

For now at least, Obama is savoring victory; he looks strong, principled and effective for getting something huge done in a city many Americans detest.

Still, the near-term reward could easily be forgotten come November.

This campaign season already has been unforgiving for the White House and the Democratic Party, with a monumental loss in the Massachusetts Senate election and a spate of debilitating congressional retirements. And conditions seem ripe for the electorate to punish the party in power.

Voters are furious. They hate Washington. They also detest incumbents. They're concerned most about the economy. And unemployment that's hovering near 10 percent. They're also split over whether Obama's health plan is good for a nation with enormous budget deficits and climbing debt.

How those variables play out is anyone's guess.

Even so, Obama reassured rank-and-file Democrats before they cast what he rightly called a tough vote.

"It will end up being the smart thing to do politically because I believe that good policy is good politics," the president said Saturday at the Capitol.

Nearby, enraged tea party protesters filled the grounds and the steps of adjacent office buildings, railing against the measure and promising to fire lawmakers who backed it. Some cursed and yelled racial epithets at black lawmakers.

Protesters were back Sunday, the message the same: "Kill the Bill."

Ahead of the vote, a Gallup poll showed more Americans believe the measure will make things worse rather than better for the country as a whole and for them personally. And most polls show most people don't like the plan although some surveys showed Americans giving high marks to individual elements.

"It's very unusual that you have a major policy that doesn't have a majority of support in the public," said George Edwards, a Texas A&M University presidential historian. "When they enjoy the benefits of the bill, they may come around. But that may take some time."

Also unclear is how voters will treat Republicans. Some of the measure's elements go into effect immediately, such as coverage for children on their parents' policy until age 26 and prescription drug benefits for seniors. Republicans could be tagged obstructionists if the electorate likes these provisions and if the economy improves.

From now on, Obama and the Democrats will promote the measure's benefits while countering Republican nay-saying and griping about process. The president also will focus primarily on voters' most pressing concern — jobs. And that may endear him to voters more than the passage of his signature domestic issue.

Obama's immediate concern is holding Democratic majorities in Congress. His own political re-election is a while off, but the White House is almost surely focused on it, too.

His job-performance rating is hovering near 50 percent and may not rise even after he put so much political capital on the line.

Past presidents have either seen their poll numbers stay the same or dip following passage of divisive, though history-making, measures.

That was true for Lyndon B. Johnson's Civil Rights Act and Great Society agenda in the 1960s, Ronald Reagan's economic measures in the 1980s, and George W. Bush's tax cuts in the early 2000s. The exception was Bill Clinton, who saw his support increase in the 1990s after signing a contentious budget measure and welfare reform legislation. But it eventually fell.

Obama's political boost may come later.

"There's a bump for the history books," said Fred Greenstein, a Princeton University presidential scholar. "When historians ask if this is a kind of squandered presidency, there will be health care to point to."

The immediate future is less certain.

Will voters give Obama credit for addressing the issue if many Americans won't feel most changes immediately? Or will voters punish Democrats for a year of partisan wrangling that has exacerbated Americans' anti-Washington feelings and diverted focus from the economy? Will health care even be on the minds of Americans struggling through recession?

Throughout the yearlong debate, the GOP derided the bill as "socialized medicine" and warned that it would be devastating. But Republicans may find themselves looking sheepish given that the status quo won't change for most people for years.

Democrats now have an accomplishment around which to unite. Also, critical constituencies like senior citizens and young voters will feel change soon. And independent voters may praise Obama for showing that a Democratic majority can make Washington work.

Still, Democrats face a public fed up with Washington and disappointed by a president elected to change it. A year of bitter haggling and legislative maneuvering may feed into the argument — successfully stoked by Republicans — that Democrats have failed to fix Washington.

That's the reason some Democrats now worry about losing control of Congress.

"The voters will have their say on the politics," says White House press secretary Robert Gibbs. Still, he adds: "The president was and the Congress were sent here to address the problems that people face in this country, and that's what voters want us to see."

___

EDITOR'S NOTE — Liz Sidoti has covered national politics for The Associated Press since 2003.