Sen. Hillary Rodham Clinton, $6.4 million poorer but still rich in tenacity, pledged yesterday to remain in the presidential race "until we have a nominee."

But for many other Democrats, the key question for the long Democratic battle had shifted from who to when, after an election night Tuesday that put Illinois Sen. Barack Obama still farther ahead of the New York senator, whose nomination had once seemed all but inevitable.

Former South Dakota Sen. George McGovern, who had endorsed Mrs. Clinton early in the race, switched his allegiance yesterday to Mr. Obama in the wake of the North Carolina and Indiana results. He is not a superdelegate, but his decision had special resonance for the Clinton campaign, as both she and her husband, former President Bill Clinton, had been tireless workers in his unsuccessful 1972 presidential bid.

Mrs. Clinton managed to pick up one superdelegate yesterday, as North Carolina Rep. Heath Shuler followed the lead of his district, which supported Mrs. Clinton in Tuesday's balloting.

But, following a months-long pattern, it was once again Mr. Obama who was the net winner of new endorsements from the party officials with automatic entree to the national convention floor in Denver.

One of those endorsing Mr. Obama, Virginia's Jennifer McClellan, like Mr. McGovern, formerly had been committed to Mrs. Clinton. The other three, according to The Associated Press, were North Carolina Democratic Party Chairman Jerry Meek; Jeanette Council, a North Carolina member of the Democratic National Committee; and Inola Henry, a California DNC member.

At a news conference in West Virginia, where she is a heavy favorite in next Tuesday's primary, Mrs. Clinton shrugged off suggestions that the unprecedented competition was effectively over. She also rejected the notion that the lengthy conflict would split her party or otherwise hinder the eventual nominee.

"I just don't believe that. We've had a historic, record turnout by both of us bringing people into the Democratic Party," she said. "People are actually voting for Democrats, and I think we can build on that."

Gerald McEntee, president of the American Federation of State, County and Municipal Employees, or AFSCME, a union that has spent hundreds of thousand of dollars promoting the Clinton campaign, also expressed frustration with what he sees as an imprudent rush to end the Democratic competition at the expense of the candidate he sees as the stronger potential nominee. He warned that the first-term Illinois senator offers a big target for the GOP.

"[Republicans] will have a dossier on Barack Obama like you never saw, that is second to none," he predicted in an interview yesterday. "The flag pin, Reverend [Jeremiah] Wright, the Pledge of Allegiance, the Weathermen, [the candidate's wife] Michelle Obama saying she was proud of America for the first time in her life -- they are going to build on all of that and try to pull him down.

"We need a Democrat in the White House, but we are frightened that there are problems already [with Obama]. If not, they'll find them, and we'll be in the fight of our lives."

But another labor leader, Anna Burger, secretary-treasurer of the rival Service Employees International Union, or SEIU, was among the first to call for Mrs. Clinton to leave the field, issuing a statement shortly after Tuesday's results were announced.

"Senator Obama's commanding win in North Carolina and close showing in Indiana means he is clearly the Democratic nominee for president," Ms. Burger said. "We've had a long process, and the outcome is now clear. The Democratic Party should come together to focus on winning in November."

In an interview on National Public Radio, Pennsylvania's Gov. Ed Rendell, a warrior for Mrs. Clinton in the campaigning that led to her big win in the state's primary April 22, said no one should be in a hurry.

"I think Senator Clinton is going to win crushing victories in West Virginia and Kentucky and Puerto Rico and hold her own in the other states," he said, according to a transcript posted on the Time.com Web site. "People should take advantage of the polls and figure out the electoral math. ... It's going to be an interesting three or four weeks."

But, conversely, Pennsylvania Rep. Mike Doyle, D-Forest Hills, an uncommitted superdelegate, left little doubt about his view of the campaign's direction.

"The math does not look good for her: She lost North Carolina by 230,000 votes and won Indiana by 23,000. The race for delegates is over. She can't get within 100 [delegates] of Obama now," he said in a phone interview.

"You have to wonder if she's thinking about an exit strategy," Mr. Doyle added. "I don't think there's any doubt that, in her heart, she wants to do the right thing -- but on her own terms. The next couple of days will be critical days for her. She has to be the one to decide her own destiny, and the hope is she will make a conclusion that is in the best interests of the party."

In a conference call with reporters yesterday, Clinton aides continued to argue that their candidate would be better able to defeat the presumptive Republican presidential nominee, Arizona Sen. John S. McCain, in the fall.

"Many pundits have counted Senator Clinton out many times during this contest," said her spokesman, Howard Wolfson. "Thankfully for us, the voters control this process, not the punditocracy."

Mr. Wolfson also confirmed that the candidate had loaned her campaign another $6.4 million over the last month, in addition to the $5 million she had invested before her popular-vote victories in Texas and Ohio.

On a rival call to reporters, Obama campaign manager David Plouffe proclaimed: "We can see the finish line." Even before the day's movement of superdelegates, he said his campaign's tally showed Mr. Obama to be within 172 votes of a nominating majority.

According to the AP tally, the delegate race yesterday stood at 1,846.5 for Mr. Obama, and 1,696 for Mrs. Clinton, with 2,025 needed to win the nomination.

Through the course of the campaign, these dueling conference calls have often been punctuated by sharp jabs from both sides, but a more respectful tone was evident yesterday.

In response to a question, Missouri Sen. Claire McCaskill, a key Obama supporter who joined Mr. Plouffe's call, rejected the opportunity to call for Mrs. Clinton's withdrawal. "It would be inappropriate and awkward and wrong for any of us to tell Senator Clinton when it is time for the race to be over. It is her decision, and it is only her decision, and we are confident that she is going to do the right thing."

After her midday West Virginia appearance, Mrs. Clinton returned to Capitol Hill for a series of meetings with uncommitted superdelegates.

While she heads today to campaign appearances in West Virginia, South Dakota and Oregon, Mr. Obama, who was off the campaign trail and at home in Chicago yesterday, was to return to Washington for a similar round of private lobbying today.