Jeb Bush ran Florida for two terms as Governor, leaving office with astronomic approval ratings, which makes him by far and away the Republican Party’s best bet to hold the Senate seat being vacated by Mel Martinez’ retirement.  But will Jeb Bush feel comfortable as a legislator rather than an executive?  And will his family name wind up being a hindrance as his brother leaves the White House?  Better yet, will Jeb even run for the office?

As Caroline Kennedy pursues her bright-lights, big-city bid for the U.S. Senate, another child of dynasty is quietly testing the waters for his own Senate run.

Former Florida Gov. Jeb Bush – the son of one president and the brother of another – has been working the phones since Sen. Mel Martinez (R-Fla.) announced earlier this month that he won’t seek reelection in 2010. Sources say Bush hasn’t made up his mind yet about running for Martinez’ seat yet, but that he’s getting green lights from would-be contributors and blessings from Republican Party leaders.

Strategists and political observers take it as a sign that Bush will run.

“Everything indicates that he’s in,” said David Johnson, a Republican Strategist and the CEO of Strategic Vision. “You’re not making calls and laying the ground work for fundraising unless you’re clearing the field for your candidacy.”

The “dynasty” crack is more than a little unfair.  Jeb Bush has worked his way to power, doing the kind of party building that his older brother more or less skipped on his rise to the presidency.  He served for two years as Florida’s commerce secretary, ran successful political campaigns for other Republicans, lost his first election to Lawton Chiles by a whisker and returned the next gubernatorial election to handily defeat Chiles’ lieutenant governor, Buddy McKay.  He then ran the state of Florida for eight years, and did so well enough to leave office with over 60% approval ratings last year on his way out the door.

In contract, Caroline Kennedy endorsed Barack Obama, and then supposedly helped vet his VP options.  She helped come up with Joe Biden, who will end his political career by becoming the luckiest non-entity in American politics.  That’s the entire extent of her experience in public service.  And Kennedy wants an appointment, not an election.

Republicans want him to run, but predictions are mixed as to whether he will actually do it.  His outreach to party leaders and big contributors encourages some, but others still have their doubts.  Jeb has never been a legislator; like his brother George, he has only been an executive, and may not like the idea of becoming one of 100 voices instead of the final word.  With his brother leaving office with the inverse of Jeb’s approval ratings, he may find himself with less influence in Obama’s Washington — and with the GOP barely hanging onto the filibuster at the moment, prospects for making a big difference on policy look grim indeed.

Still, Jeb has been a devoted party man for the last 20 years and more.  I’d guess he will run for one simple reason: he may be the one Republican in Florida who can easily win the seat.  Unless someone with more standing materializes, Jeb will step up to the plate to keep the GOP in the game.