Democrats in Congress who haven’t yet declared their presidential preferences are still hanging back, studiously avoiding any suggestion that Sen. Hillary Rodham Clinton quit the race after a worse-than-expected performance in Indiana and North Carolina.

Every Democrat in the House and Senate has an automatic delegate slot at the Democratic National Convention, which makes them swing voters in a close nomination battle.

After a bruising 14-point loss in North Carolina and a narrower-than-anticipated 2-point win in Indiana this week, Clinton trails Illinois Sen. Barack Obama, 1,840 delegates to 1,684 — not including Florida and Michigan, which have been stripped of their delegates because their January primaries broke party rules.

Obama was due on Capitol Hill Thursday for private meetings with congressional superdelegates. Clinton, D-N.Y., is pressing on with the race, with West Virginia, Oregon, Kentucky, Puerto Rico, Montana and South Dakota still to vote.

Her backers on the Hill aren’t abandoning Clinton, but they’re doing the math.

“I don’t know if the fat lady has sung yet, but she’s clearing her throat,” said Rep. Tim Ryan of Ohio, who endorsed Clinton last month.

House Speaker Nancy Pelosi, D-Calif., and Senate Majority Leader Harry Reid, D-Nev., made clear Wednesday they do not intend to call for an early end to the contest.

“My belief is the race should continue. People should have an opportunity to vote,” Pelosi said. “As long as a campaign is going on and candidates are in the race, there’s a chance.”

If Florida and Michigan delegations are not seated, it will take 2,025 delegates to win the nomination.

Neither Obama nor Clinton are on track to win enough pledged delegates to reach that sum. That means the winner will be put over the top by superdelegates, the elected officials and party leaders who are not bound to support any candidate.

Clinton currently holds a narrow lead among the nearly 800 superdelegates — 271 to 256 — but would need to win the vast majority of the remaining undeclared superdelegates, or convince some of Obama’s backers to flip.

In 1980, Sen. Edward M. Kennedy, D-Mass., tried to persuade delegates pledged to President Carter to switch to his insurgency — including, according to one biographer, then-Arkansas Gov. Bill Clinton.

Kennedy, a longtime Obama supporter, said Wednesday that the Illinois senator has the nomination “effectively sewed up” and “I don’t see any possibility of altering or changing that inevitable fact.”

“I think he’ll have a surge of support,” said North Dakota Sen. Kent Conrad, who lined up behind Obama late last year. “Because Indiana was so close and he won such a big victory in North Carolina, we will now see more superdelegates coming to his side.”

Conrad said he believed superdelegates would clinch the nomination for Obama before the June 3 end of the primary calendar, even as many of his colleagues said they’re staying on the fence.

“I made a decision a year ago about staying neutral and I’m staying with it,” said Oregon Sen. Ron Wyden. His state votes May 20, and the senators from Montana, Max Baucus and Jon Tester, said they do not plan to endorse before their state’s June 3 primary.

Still, undeclared superdelegates said they could feel the winds change.

“The landscape is very different today than it was yesterday,” said Rep. Jason Altmire, a Pennsylvania Democrat who says he plans to remain neutral. He said the most active Clinton supporters in the House had been upbeat before the May 6 contests. “Those very same people, the air is let out of them,” he said.

Eleven Democratic senators said they, too, remained unwilling to commit to either presidential candidate.

Defense Appropriations Chairman John P. Murtha, a Pennsylvanian who campaigned for Clinton in his home state, said, “A lot of the superdelegates that might have been ready to get behind Hillary after Pennsylvania are now hesitant.”

Another part of the Clinton camp, though, sounded more optimistic. “Within a week we have the next primaries, I think she’ll do very well there,” said Sen. Robert Menendez of New Jersey.

With Obama closing in on the nomination, Clinton backers in Congress grasped for hopeful analogies.

“I’m used to those last-minute passes that bounce off people’s helmets,” said Rep. Steve Israel, who watched wide receiver David Tyree set the table for the New York Giants’ Super Bowl victory this year by leaping and pinning a pass against his helmet as he tumbled to the ground to keep the game-winning drive alive.

Hopeful as some Clinton supporters are, others are looking for her to provide better evidence that she can win.

“I always go with the guy who brung me. In this case, it’s a girl ... On the other hand, I don’t want to rip the party asunder,” said Sen. Dianne Feinstein of California. “I think in this one, the key is really in the strategy and whether the strategy is workable.”

— Alan K. Ota, Edward Epstein, Bart Jansen, Marie Horrigan, David Nather and Catharine Richert contributed to this story.