Birch Bayh's mood still fluctuates between hurt and anger.

George McGovern is relieved that it's over, and is getting more speech invitations than he has since he ran for president.

Frank Church, who almost died of cancer 30 years ago and has viewed life through fatalistic eyes since, is spending most of his time shoring up the emotions of his shell-shocked staff.

Warren G. Magnuson, who had never lost an election in almost a half-century in politics, is licking his wounds in Palm Springs, Calif., and it has been touch and go whether he would return to Washington at all to wrap up his chores as keeper of the Senate appropriations process.

Less than two weeks ago they were mightly figures, powerhouses of the Democratic Party, men who had reached for the presidency, influenced foreign policy, chaired the Senate's key committees. Three short buzzes put an elevator at their command, the right code held a subway car till they arrived.

But this week, as the first of the beaten liberals of 1980 traipsed back to Capitol Hill, all that was ending as abruptly as if it had never been. The dreams were over, the power oozing away in the worst case of liberal hemophilia since the end of World War II.

Few of the losers had a solid hold on the future. Church was thinking about teaching; McGovern was setting up an organization called the Coalition of Common Sense and mentally toting up his lecturing fees; Herman E. Talmadge was bemoaning that fishing would not be enough to get him through retirement; Bayh was toying with the hope of becoming chairman of the Democratic National Committee so he could strike back at the bad guys who brought him down.

"They still don't know what hit them," said one of the Senate's top Democratic aides. "It just hasn't sunk in. It's sinking in a lot faster on the rest of us. There are several thousand Democratic staffers up here who thought this was a way of life. It's not an easy time for used and bruised Democratic staffers."

In the meantime, the lame-duck session of the Senate was lamer than any in memory. In the basement of the Senate office buildings, the cafeteria talk was about job-hunting, not legislation. And few of the dethroned senators or their aides were thinking even half-seriously about one last chance to pass pet bills or cap careers with a final Senate coup.

"Most of us don't feel this lame-duck session should deal with anything very important," said George Cunningham, McGovern's administrative assistant. "The mood of the country has changed so dramatically it wouldn't even be proper to do anything other than the housekeeping chores. It somebody else's ballgame now."

Several of the losers hadn't even bothered to come back by the end of the week.

Magnuson, chairman of the Appropriations Committee, was holed up in his California desert home even though the only real business of his last Senate moments was appropriations bills. His aides said Magnuson would return to Washington this weekend.

Church, vacationing with his family, is due back sometime next week. Bayh, buried in a Republican avalanche 10 days ago, tried to get away from it all with his son in Florida -- and found irony that his holiday was impaired by the rains from a storm there.

McGovern gave the impression of being the calmest of the losers, having known it was coming weeks before Election Day.

He is fond of telling of a campaign incident that let him know it was all over more certainly than any pollster could have. In the waning days of his last South Dakota campaign, he was making his way through a supermarket when he met two elderly women wearing campaign buttons for Ronald Reagan and James Abdnor, McGovern's opponent.

The women told McGovern he was going to get beat because he didn't vote right, he was wrong on the issues. He had gone the wrong way on the Panama Canal treaties, the South Dakotans told their senator. Then they bought their groceries with food stamps -- a program the farm-state liberal had pushed for years -- and McGovern says he knew the game was over.

The game was over for more than the losers. The bleakest-looking Democrats in the Senate this week were the men who didn't run in 1980 -- Majority Leader Robert C. Byrd (D-W. Va.) and a host of committee chairmen who were thrust overnight from their seats of power to uncomfortable places in a distraught minority.

Most of them were trying to sort out their uncertain futures and listening to the scuttlebutt about the New Right's newest 1982 target lists. There were little touches of irony there, too.

Sen. Henry M. Jackson (D-Wash.) had lost his chairmanship, and his name was being handied about in the press as a potential secretary of defense in the new Reagan administration -- but the National Conservative Political Action Committee had his Senate seat targeted in 1982 anyway.