Two sources close to Jeb Bush, including one who has spoken to the former Florida governor within the past few hours, say he is seriously considering a run for Senate now that incumbent Republican Mel Martinez has retired.

"He is receiving a lot of encouragement from both in and out of the state," an longtime Bush adviser said tonight. "He is going to take his time and approach this very methodically."  Bush will weigh, according to this adviser, how a run would impact his family, his business, and whether the Senate would be the best platform for the causes he'd advocate -- education, immigration, GOP solutions to health care and energy.

Bush did not respond to an e-mail seeking comment.

If he decides to run, Republicans expect the field to clear for him.  Maybe. Gov. Charlie Crist, with whom Bush has not had the warmest of relations, is said to be interested in moving to the Senate. Florida Attorney General Bill McCollum is weighing a bid, as is former state House Speaker Marco Rubio, Orange County executive Richard Crotty, and U.S. Rep. Connie Mack.

Bush, in an interview with Newsmax this week, said that the GOP risked becoming "the old white-guy party" and that it ought to modulate the way it handles the immigration issue. Bush, who speaks fluent Spanish and won the support of a majority of Hispanic voters during his 2002 re-election bid, favors a comprehensive approach to reform. But Bush said that Republicans can't give up on conservatism, and, in what might be interpreted as a dig at Florida's current governor, said that Republicans "can't be Democrat-lite. We can't just 'get along."  The words echo some Republican criticism of Crist, who they view as accodomationist in his politics and unwilling to push for real reforms.

Alex Sink, Florida's chief financial officer, has said she'll run for re-election in 2010 but might change her mind in the wake of Martinez's announcement.