WASHINGTON (CNN) -- A top Michigan Democrat expressed frustration Wednesday with Sen. Barack Obama for not embracing a plan to conduct a revote of the state's Democratic primary.

"The road to a Democratic White House goes through Michigan and Florida," Sen. Hillary Clinton says.

The source's comments come the same day Sen. Hillary Clinton accused her rival for the Democratic presidential nomination of being "un-American" for not backing plans to hold a revote in the Michigan and Florida primaries -- a charge Obama rejects.

Lawmakers in Michigan faced mounting pressure Wednesday to come up with an agreement before the legislature adjourns Thursday for a two-week recess.

"The Obama people are blocking it in the Legislature," the Democratic source tells CNN. The source also says the group has repeatedly and unsuccessfully reached out to the campaign for input and cooperation.

The source says that Obama's campaign has been asked to craft an alternative or to meet with the Clinton campaign to work out an acceptable compromise, but that those requests have been met with silence.

But in an exclusive interview with CNN's Anderson Cooper on Wednesday, the Illinois senator hit back at Clinton's claims that he is standing in the way of revotes in Florida and Michigan.

"Sen. Clinton, I have to say on this, has been completely disingenuous. She said, when she was still trying to compete with the votes in Iowa and New Hampshire, that Michigan and Florida wouldn't count," he said.

"Then, as soon as she got into trouble politically and it looked like she would have no prospects of winning the nomination without having them count, suddenly she's extraordinarily concerned with the voters there."

"I understand the politics of it, but let's be clear that it's politics," he added. "I want the Michigan delegation and the Florida delegation to be seated. And however the Democratic National Committee determines we can get that done, I'm happy to abide by those rules."

The Clinton campaign has been increasing its criticism of Obama, even challenging the Illinois senator to back the seating of a full Michigan delegation.

"Sen. Obama speaks passionately on the trail about empowering American people. Today, I am urging him to match those words with actions to make sure people of Michigan and Florida have a voice and a vote in this election," Clinton said at a campaign rally in Detroit, Michigan, on Wednesday.

"This is a crucial test [for Obama] -- does he mean what he says or not?"

Michigan and Florida held primaries in January, but the national party stripped them of their delegates for scheduling their contests too early.

Michigan has 157 Democratic delegates at stake, and Florida has 211.

Florida has nixed the idea of a revote, but a proposal for a June 3 election in Michigan is under consideration.

Looking ahead to the general election, Clinton said ignoring the votes in Michigan and Florida would be a "grave mistake."

"The road to a Democratic White House goes through Michigan and Florida, and if Democrats send the message that we don't care about your votes, I'm sure John McCain and the Republicans would be happy to have them," she said.

Clinton, who was the only main contender on the ballot in Michigan, won with 55 percent of the vote. Some 40 percent of Democrats in the state filed ballots declaring themselves "uncommitted."

After the Democratic National Committee's decision, Obama was among the Democratic presidential contenders who had their names taken off Michigan's ballot.

"When others made the decision to remove their names from the ballot, I didn't because I believed your voices and your votes should count," Clinton said.

Michigan Democratic leaders want their delegates seated, but the party has been unable to reach a consensus on how to handle them.

Michigan Sen. Carl Levin, who has been a major proponent of a new primary vote, told CNN on Wednesday that his group of four unaligned Michigan politicians was hopeful that legislators would vote on the plan Wednesday evening or Thursday, which would allow the delegation to be seated "without a floor fight and without a credentials fight."

But Michigan state Sen. Tupac Hunter, a major Obama supporter, says an "overwhelming majority" of members who support both candidates "find something or the other wrong with it and cannot support it in its current form. A new vote, he added, "does not look likely."

"From where I sit, there are no floating pieces to this," said Hunter -- nothing that can be changed that wouldn't require a major alteration or abandonment of the current proposal. "I'm not sure how feasible it is at this point. ... There's nothing I've seen or heard that would lead me to believe that there's going to be an agreement."

He called on DNC Chairman Howard Dean to step in immediately and broker a compromise, to help avoid a "chaotic convention."

"There's a lot of hot rhetoric out there. Sen. Obama and Sen. Clinton, they're in the throes of a campaign, we understand that," he said. "But the DNC needs to come in and calm the storm."

On Tuesday, Obama campaign spokesman Tommy Vietor said, "The Clinton campaign favors whatever they think will benefit them."

Shortly before Clinton's speech, the Obama camp released a letter outlining concerns it had with a potential revote in Michigan.

"There are such questions, and they are serious both in nature and in their potential, if not likely, impact on the June election proposal," Obama counsel Robert F. Bauer said in the letter.

One of the concerns listed was voter disqualification.

Michigan voters wanting to cast ballots in the new primary would have to identify themselves as Democrats and certify that they didn't vote in the state's Republican primary in January. Michigan usually does not require party identification in primary elections.

Some say this requirement is unfair to Democrats who voted in the Republican contest, knowing their party's primary was invalid.

A memo from the Clinton camp countered this argument, saying Obama can't argue that supporters participated in the GOP primary instead of the Democratic one because "the Obama campaign's allies in Michigan organized an effort to get people in Michigan to vote for 'uncommitted' in the Democratic primary."

The Clinton camp also pointed out that Obama agreed to comply with DNC rules, which prohibit crossover voting.

The Obama memo also questioned whether the revote proposal could be cleared in a timely manner, without putting too much strain on election preparations and possibly leading to time-consuming litigation.

The draft proposal under consideration in Michigan calls for a new Democratic primary on June 3, to be paid for with private money. The state Legislature would have to approve that plan.

The DNC issued a statement Wednesday saying the proposal meets the basic requirements of the national party's delegate selection rules.

State Senate Majority Leader Mike Bishop, a Republican, has said he will not give his support to any plan that does not have the consent of all the parties involved, including both presidential campaigns.

Neither Clinton nor Obama may get enough delegates -- 2,024 -- to clinch the nomination before the national convention in August. Clinton is trailing Obama in delegates -- 1,479 to 1,621. E-mail to a friend

CNN's Rebecca Sinderbrand, Jessica Yellin, Alexander Mooney, Peter Hamby and John Roberts contributed to this report.

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