WASHINGTON - U.S. Senate Majority Leader Harry Reid may pay the ultimate political price for championing President Barack Obama's liberal agenda: He could lose his seat back home in Nevada.

Such an outcome in the November congressional election would be a serious blow, not just to Reid -- a major Obama ally in the drive to revamp U.S. healthcare -- but to the president and the Democratic Party.

If Republicans can knock off Harry Reid, they will have scored an enormous victory, said Paul Light of New York University's Center for the Study of Congress.

They will celebrate (it) as a sign that the country is changing and moving toward a possible defeat of Obama, who is up for re-election in 2012, said Light.

Reid, seeking a fifth term, is seen as among the most vulnerable Senate Democrats seeking re-election this year, and the defeat of any one of them would change the balance of power in Washington.

Democrats now hold 60 votes in the 100-member Senate, the number needed to clear Republican procedural hurdles. If Republicans pick up just one seat, they can block Obama and his fellow Democrats on matters ranging from judicial nominees to spending bills.

Reid's predecessor as Democratic Senate leader, Tom Daschle of South Dakota, lost his re-election bid in 2004, becoming the first Senate party leader voted out of office in more than half a century.

Kenneth Fernandez, a political science professor at the University of Nevada, Las Vegas, said Reid's dual roles as Senate leader and Nevada's senior senator hurt him.

He has to represent Nevada and be a national Democratic leader, Fernandez said.

This hurts Harry Reid because you have a fairly even number of registered voters on both sides, Republican and Democrat, in Nevada, a socially liberal but fiscally conservative state.

Independent polls show Reid running behind three potential Republican challengers, none of whom is seen as a political heavyweight but one of whom will likely be picked in June as the party's nominee.

Surveys also show that Nevada voters, six years after electing Reid to a fourth term with 61 percent of the vote, simply do not like their tough yet uncharismatic senator.

A survey of 625 registered Nevada voters in January -- by Mason-Dixon Polling & Research -- found 52 percent had an unfavorable opinion of Reid, while 33 percent had a favorable one and 15 percent said they were neutral.

The nonpartisan Rothenberg Political Report this week moved the Reid's race from tossup to lean takeover in favor of Republicans.

Still, analysts say a better picture of Reid's prospects will emerge when it becomes clear who his Republican challenger will be.

Reid has drawn comfort from the fact that some powerful business leaders and Republicans in Nevada, recognizing his ability to help the state, have rallied to his side.

In addition, Reid appears headed to raise $25 million, more than enough to air a crush of TV and radio ads.

'DEAD MAN WALKING'

A lot of people see Harry Reid as a 'dead man walking,' but he still has plenty of spring in his step, said Eric Herzik, who heads the political science department at the University of Nevada, Reno.

Harry Reid is not a beloved politician. He is a power politician, Herzik said. I think Harry Reid will win. But will I guarantee it? No.

Last month, Reid was hailed by Obama, congressional analysts and others for winning Senate passage of legislation to overhaul the U.S. healthcare system.

But in Nevada, as well as much of the rest of the United States, the bill has proved to be highly unpopular.

A telephone survey released this week by Rasmussen, a private polling firm, found 39 percent of Nevada voters supported the legislation and 54 percent opposed it.

The Senate majority leader has also been dogged in Nevada by an anti-incumbent mood fueled by a double-digit jobless rate and one of the highest home foreclosure rates in the country.

Reid's troubles mounted last week with the disclosure that in 2008 he suggested Americans may be willing to elect Obama as the first black president, saying he was light skinned and had no Negro dialect.

While Republicans called for Reid to step down as Senate leader, Reid apologized to Obama for a poor choice of words. Obama accepted Reid's apology, saluting Reid as a longtime champion for social justice.

Obama plans to go to Nevada next month to talk about jobs and the economy, and to try to help out Reid.

Obama's visit should energize the Democratic base, and Reid needs the full support of that base to win, Herzik said. Obama will give Reid's campaign a needed dose of charisma.

(Additional reporting by Ed Stoddard and Dan Whitcomb in Los Angeles; Editing by Matthew Bigg and Peter Cooney)

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