The Illinois senator spoke to about 1,000 donors in a Manhattan ballroom, all of whom had paid at least $1,000 to attend. Many were Clinton supporters until she dropped out of the race last month.
Obama praised the former first lady as tough and smart. "She wore me out," he said to laughs.
The Democratic nominee-in-waiting then wrapped up his speech and thanked the audience, moving to shake hands along a rope line.
After a minute or so, the music was cut short and Obama returned to the stage.
"This is not the speech part, but it is important," he said sheepishly, urging the group to reassemble.
"Senator Clinton still has some debt, and I could have had some debt if I hadn't won. So I know the drill," Obama said, encouraging donors to use the forms under their seats to make a contribution to help her.
"It's very important to us, and obviously Senator Clinton will be grateful as well," Obama said.
Things went a bit more smoothly a few blocks down Park Avenue, where Clinton introduced Obama at a smaller fundraiser that netted about $4.1 million for the joint Obama/Democratic National Committee Victory Fund.
"Whatever brings us here tonight I hope is understood to be not only unifying but transcendent," Clinton told the 125 major donors.
Obama, in turn, echoed Clinton's call for unity.
"With just half a wing this bird can't fly," he said.
The two flew together to New York from Washington for the fundraising swing and were to appear together at a breakfast Thursday morning. An event to help Clinton with her campaign debt was canceled because of Senate votes in Washington.
