A Clinton spokesman, Mo Elleithee, said of the Michigan proposal: “Nearly 600,000 Americans participated in the Michigan primary in January, and we have a solemn obligation to ensure that their voices are heard. The best way to make that happen is to honor their votes, but if that isn’t possible there should be a new state primary that doesn’t leave taxpayers footing the bill.”

He said the Clinton campaign was waiting to hear more details.

The plan was negotiated by Senator Carl Levin, Representative Carolyn Cheeks Kilpatrick, Debbie Dingell, a member of the Democratic National Committee, and Ron Gettelfinger, president of the United Auto Workers. The four Democrats, who all claim neutrality in the presidential contest, have been working with state and national party officials and representatives of the two campaigns to try to find a solution to the delegate impasse.

“We agree that the Michigan delegation should be seated at the convention, and without a fight before the Credentials Committee or on the floor of the convention,” they said in a statement Friday afternoon.

A person close to the negotiations, who requested anonymity to discuss private talks, said the Clinton campaign was receptive to the June revote plan but the Obama forces were holding back for now.

The person said that Michigan Republicans, who control the State Senate, said they would not stand in the way. But Democrats, who control the state House of Representatives, are divided between Clinton supporters and Obama supporters. “The Clinton people say they’re not going to block it,” the source said. “The question is what the Obama people are going to do.”

The situation in Florida seemed more intractable, with Clinton supporters arguing the party’s prospects in November could be jeopardized if a satisfactory resolution is not found. Some Clinton backers said they were intentionally withholding their contributions to the party, arguing that Howard Dean, the D.N.C.’s chairman, has left the situation in the hands of the states and the candidates, as opposed to exercising leadership to resolve it.

“My wife and I could max out, and we won’t,” said Ira Leesfield, a Miami lawyer who has given $61,500 to the committee since 1997. “We’re dissatisfied with the D.N.C. not taking the bull by the horns.”