TALLAHASSEE, Fla. (AP) --
"I can play a role in helping to reshape the Republican Party's message and focus on 21st century solutions to 21st century problems," Bush told The Associated Press in a phone interview. "Not running does not preclude me from being involved in these things and I will be."
Bush seriously considered a run after Martinez said last month he wouldn't seek a second term. Bush spoke with senators, supporters and family, including his brother, President George W. Bush, and his father, former President George Bush.
He said his decision wasn't based on politics, but on his "personal journey." He said his brother's low approval rating didn't factor into his decision, and that Floridians are familiar with his record as governor.
"One of the benefits of being governor is people get to know you and I think people know I love this state," Bush said. "While I'm proud of my brother and I love my brother ... people know that I'm Jeb Bush and I don't think that would have been a problem."
And he said he was ready for people to attack him based on his name, saying he already endured that when he ran for re-election in 2002 while his brother was in the White House.
"That's just part of the game, you take the good with the bad and that was not an issue," Bush said.
Those close to him have speculated for years that he wouldn't have an interest in the Senate because his personality is more suited for executive leadership, and that being one of 100 senators would be frustrating for Bush. Bush said that also wasn't a factor.
"I really felt like I could make a difference and it could have been a fulfilling job," Bush said.
Bush won bipartisan praise for leading the state through eight hurricanes over a two-year period. He used standardized testing to overhaul the education system, was credited with making government more efficient and lowered taxes.
Bush served as governor of Florida from 1999-2007 and remains a popular figure in the state. His announcement clears the path for several other potential Republican candidates who had said they wouldn't challenge him.
"All of us are disappointed that Jeb didn't run, but now it's time to move on," said former House Speaker Allan Bense, who said he would decide by the end of the week if he will run. "I'm very interested."
Bense's successor, former Speaker Marco Rubio, is also very interested. He has already set up a campaign-like Web site and said he will announce a decision in two to three weeks.
Other potential Republican candidates include Attorney General Bill McCollum, as well as several congressmen.
"I understand his decision. Jeb would have been a great candidate and senator. The good news is that Republicans still hold the advantage with a deep field of potential candidates," said Martinez, who announced last month that he wouldn't seek a second six-year term.
Republican Party of Florida Chairman Jim Greer said he expects the field of potential candidates to narrow as people look at the resources needed to win. He also said Gov. Charlie Crist would have some sway in candidates' decisions.
"The governor is going to play a very important role in determining who the next United States senator from Florida is," Greer said. "Any credible candidate will certainly realize that they're going to need to have a conversation with Gov. Crist about the race and I know the governor is going to be very committed to ensuring that the seat remains Republican."
Democrats considering a run include Chief Financial Officer Alex Sink, state Sen. Dan Gelber and U.S. Reps. Allen Boyd and Kendrick Meek.
"It is clear that Florida will be a central battleground in the 2010 election," said Florida Democratic Party Chairwoman Karen Thurman in a statement. "Over the past several years, Democrats have made major gains in Florida, winning three of the six statewide elections."