Senator Obama is sweeping through New York in an attempt to unify the Democratic Party before the general election by appearing alongside Senator Clinton at a fund-raiser this morning and encouraging his supporters to help retire her campaign debt.

Last night, at a Manhattan fund-raiser for Mr. Obama attended by some 1,000 supporters, including former supporters of Mrs. Clinton, the Democratic nominee praised his primary rival and said he was a better candidate because of her.

In what appeared to be a gaffe, he ended his speech without asking the crowd to assist Mrs. Clinton in paying off more than $20 million in campaign debt, as had been expected.

Then, after the speech had ended and the attendees had stood up and were milling about, he interrupted the chatter. “This is not the speech part, but it is important,” Mr. Obama said. “Senator Clinton still has some debt, and I could have had some debt if I hadn’t won.”

He then directed attendees, who paid at least $1,000 a ticket, to look under their chairs for a pledge form for the Clinton campaign and encouraged his supporters to make a donation. It said: “Hillary for President” at the top.

“That is part of the process of making sure we are unified,” he said.

Outside the Grand Hyatt hotel after the fund-raiser, longtime supporters of Mr. Obama said they hadn’t contributed to Mrs. Clinton’s campaign and weren’t sure if they would, with one attendee saying “there’s low enthusiasm” among Obama backers when it comes to writing a check to Mrs. Clinton.

A former supporter of Mrs. Clinton, Bert Pogrebin, said he thought it was unbelievable that there has been so much attention given to the New York senator’s debts.

“The business of reparations at this point is absurd,” he said. The party should be focused on the future of the country, instead of Mrs. Clinton’s finances, he added.

Many longtime supporters of Mrs. Clinton say the way Mr. Obama’s campaign handles the question of her debt is central to achieving unity in the party.

A fund-raiser for Mrs. Clinton who lives on the Upper West Side and is not supporting Mr. Obama, Ricki Lieberman, said in a telephone interview yesterday that she is waiting to see whether his call for supporters to donate to her campaign is more than just an empty plea.

“There’s a lot of talk about healing and unity,” she said. “Debt relief is a way to see if it’s more than just words or if it’s an actual effort to reach out and be unifiers.”

Today’s fund-raiser is a breakfast at the Hilton for women who support Mr. Obama.

Mr. Obama and Mrs. Clinton flew to New York together yesterday, along with a member of Mr. Obama’s vice presidential search team, Caroline Kennedy, the Associated Press reported.

Last month, the two Democratic candidates for president held a rally in Unity, N.H., as part of a public effort to bring the party together after a divisive primary season.