WASHINGTON (Reuters) - Four years ago, Senator Claire McCaskill was one of Barack Obama's biggest boosters in his presidential campaign. But when he recently visited her state of Missouri, she did not have time to join him.

Many of McCaskill's fellow Democrats in Congress may also decide they are too busy to be with Obama, whose approval rating of about 40 percent as the economy struggles threatens to be a drag on their own reelection chances next year.

"You may see a number of Democrats say 'Sorry, I have a scheduling conflict,'" said a senior Democratic lawmaker.

Democrats face a big decision about whether to stand by their man in the November 2012 elections.


Many, particularly those in difficult campaigns like McCaskill, are tempted to keep their distance.

But others figure they can survive any anti-Obama backlash in their predominantly Democratic states. And they want to help their party's top star and fundraiser defeat whoever the Republicans throw at him.

More importantly, Democrats believe their best shot at retaining the Senate and taking back the House of Representatives is to help Obama rally and win a second term.

"If the president does well, we will do well," said Representative Jim McGovern of Massachusetts.

"I don't know what others will do but I say we need to run as a team," said Democratic Senator Sherrod Brown, facing a tough reelection race in Ohio. "Let's look ahead."

House Democrat Jim Moran of Virginia said: "The question is how vigorously we embrace him in terms of going the extra mile to get our people to knock on doors."

"I think we will. But the passionate idealism that we were gripped with when he was first elected has dissipated a little bit."

Some Democrats believe Obama has lost so much of his "hope and change" magic that they intend to stay away. That is particularly true if they are from a traditionally Republican or swing state, like West Virginia, hard hit by the weak economy that dogs Obama.

"In West Virginia, politics is not a team sport -- meaning hang on and do the best for yourself," said the state's first-term Democratic senator, Joe Manchin.

WILL DEMOCRATS DUCK OBAMA?

Unpopular presidents traditionally hurt their party in Congress. Voter discontent with Democratic President Bill Clinton in 1994 and with Republican President George W. Bush in 2006 were key to their parties losing control of the House and Senate those years.

It's too early to know how many Democrats will duck Obama in 2012. But it could be at least a few dozen, analysts say.

The number may rise or fall in line with how his approval rating, now at 42 percent, and the U.S. jobless rate, at 9.1 percent, move between now and Election Day.

A top Democratic aide, noting polls show most voters like Obama even though they do not approve of his job performance, said: "If his approval rating tops 50 percent and the economy improves, a lot of Democrats will want to be seen with the president."

But congressional Democrats are upset, even angry, with Obama right now.