U.S. Sen. Mel Martinez plans a major announcement in Orlando shortly, and a highly placed Republican source says Martinez will announce that he's not seeking re-election and that he may leave his seat in advance of the end of his term in 2010. That would open the door for Gov. Charlie Crist to appoint a replacement in advance of a wide-open Senate race in '10.

In another development, Democratic Chief Financial Officer Alex Sink is expected to announce later Tuesday that she will seek re-election to her Cabinet post in 2010, forgoing a possible bid for either Martinez's Senate seat or governor.

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