Clinton, who won unsanctioned contests in both states, said the results should be honored or new votes held. Obama said he abided by party rules in skipping the two contests and questioned Clinton's call now for counting them.
The two states were stripped of their delegates in a dispute with the national party, but held the contests won by Clinton anyway even though no candidates campaigned there and Obama was not even on the ballot in Michigan.
"The Clinton campaign seems to want to make up rules as they go along on this issue," Obama said. He said he would work with the national party to find a solution.
A resolution of the dispute has become vital as the two Democratic presidential contenders scratch for every available delegate in their tight battle for the right to face Republican John McCain in November's election.
Florida Senate Democratic leader Steve Geller said in Tallahassee the mail-in primary would replace the state's disputed January 29 vote, and all votes would be counted and verified by June 3.
The plan, pushed by Democratic U.S. Sen. Bill Nelson but opposed by the state's Democratic U.S. House members, calls for sending mail-in ballots to all of the state's more than 4 million registered Democrats.
The proposal will be officially released on Thursday. It will go to the state party's executive committee on April 12, and would then go to the Democratic National Committee's rules and bylaws panel for approval.