Republican Party of Florida Chairman Jim Greer tells the Associated Press Crist's formal announcement will be made Tuesday and is leaving not so subtle hints the Governor's mind is made up.

Crist has "concluded that the problems and issues that Floridians are facing-- high unemployment and the economy-- can't be solved in Tallahassee, they need to be solved in Washington, and I believe that's what he's going to do," Greer said.

Crist's popularity statewide remains very high, especially among moderates and independents; but some of the Governor's conservative base is critical of Crist's support of President Obama's economic recovery plan and his appointment of a liberal-leaning judge to Florida's Supreme Court.

Marco Rubio, the former Florida House speaker is also making a run for the senate seat and, if Crist also runs, would spark a high-profile GOP primary. Rubio is establishing himself as the more conservative choice to replace Martinez.

Crist's decision to not seek a second term in the Governor's Mansion also could spark a hotly contested race for that position. Florida's highest-ranking Democrat, State Chief Financial Officer Alex Sink, and Republican Attorney General Bill McCollum have been rumored to be considering bids for the governor's office.

That leaves at least two cabinent-level positions vacant and likely attracting a large number of candidates.

There will also be a Democratic primary for the U.S. Senate seat in 2010. South Florida congressman Kendrick Meek is the early front-runner. State senator Dan Gelber and North Miami Mayor Kevin Burns are also running in the Democratic primary.

Crist ran for the U.S. Senate in 1998, losing to then-incumbent Bob Graham.