Lacking a clear route to the selection of a Democratic presidential nominee, the party's uncommitted superdelegates say they are growing increasingly concerned about the risks of a prolonged fight between Senators Hillary Rodham Clinton and Barack Obama, and perplexed about how to resolve the conflict.
Interviews with dozens of undecided superdelegates -- the elected officials and party leaders who could hold the balance of power for the nomination -- found them uncertain about who, if anyone, would step in to fill a leadership vacuum and help guide the contest to a conclusion that would not weaken the Democratic ticket in the general election.
While many superdelegates said they intended to keep their options open as the race continued to play out over the next three months, the interviews suggested that the playing field was tilting slightly toward Mr. Obama in one potentially vital respect. Many of them said that in deciding whom to support, they would adopt what Mr. Obama's campaign has advocated as the essential principle: reflecting the will of the voters.
Mr. Obama has won more states, a greater share of the popular vote and more pledged delegates than Mrs. Clinton.
A New York Times survey of superdelegates last week found that Mr. Obama had been winning over more of them recently than Mrs. Clinton had, though Mrs. Clinton retained an overall lead among those who have made a choice. Over the past month, according to the survey, Mr. Obama, of Illinois, picked up 54 superdelegates; Mrs. Clinton, of New York, picked up 31.
"If we get to the end and Senator Obama has won more states, has more delegates and more popular vote," said Representative Jason Altmire, Democrat of Pennsylvania, who is undecided, "I would need some sort of rationale for why at that point any superdelegate would go the other way, seeing that the people have spoken."
Mr. Altmire said he was repeating an argument that he made to Mrs. Clinton during a session at her house in Washington on Thursday night with uncommitted superdelegates.