She claims she’s known since 2006 that this would be her last term. Could be, but (a) she’s changed her mind about the Senate before and (b) getting blown out by Rick Perry in the gubernatorial primary last year surely must have brought home to her what a 2012 primary would look like. Tea partiers want this seat, and one way or another, they’re probably going to get it. Why put herself through another brutal, expensive primary that’s likely to end in embarrassment?

I wonder what Olympia Snowe’s thinking right now.

Hutchison, first elected to the Senate in 1993, said the swearing-in of the new Congress, among other things, made her feel it was the right moment to announce her resignation.

She predicted that her departure from the political scene would set off a rampage of candidates looking to replace her.

“It’s just time for people to start making their plans,” Hutchison said. “Now it’s time for a new person.”

Likely Republican contenders to succeed her include Lt. Gov. David Dewhurst, Dallas Mayor Tom Leppert, state Sen. Florence Shapiro of Plano, Railroad Commissioners Elizabeth Ames Jones and Michael Williams, Weatherford car dealer Roger Williams, and Ted Cruz, a former Texas solicitor general and candidate for state attorney general.

Sound off, Texans: Who’s the favorite? Heard a lot of excitement for Williams on Twitter today after the news about KBH first broke. Via his campaign website, here he is on big government and health-care reform.

Update: A source familiar with Texas politics handicaps the race thusly:

The most amazing thing here is the level of talent that will be competing for this seat. There are several GOP candidates who are viable and would be good to great senators if elected.

Inside track – Lt Gov David Dewhurst. He’s a billionaire, so he can fund the race and defend the seat, and he holds what is actually the most powerful post in Texas government, so he has been collecting chits on this run for years.

Track 2 – AG Greg Abbott. The grassroots and Tea Parties adore Abbott. He has championed the anti-ObamaCare lawsuit, and is one of Texas’ absolute best stump speakers. He has also led a crackdown on deadbeat dads, which has earned him a lot of support in the middle.

Track 3 – Roger Williams. Former Texas Secretary of State, and he chaired the state Victory effort in 2008, raising $5 million in a couple of months. He’s wealthy, sharp, and may have the most experienced campaign talent on his side.

Track 4 – Michael Williams, Elizabeth Ames Jones, state Sen. Dan Patrick, former solicitor general Ted Cruz. Williams and Jones are both on the Railroad Commission, Williams has major grassroots support and is mindblowingly good at stump speeches, Patrick has a major Houston radio show and is very media savvy and well liked, Jones has money and some major backers of her own. Cruz is a bit of a dark horse (as is Patrick) but the grassroots love him and he’s also great on the stump. None of these candidates are bad candidates. All have held or currently hold major offices.

It will be a fascinating race to watch. There may be 20-25 candidates total on the GOP side, compared to 2 or 3 on the D side, with former Houston mayor Bill White leading that field. He was a terrible candidate for governor, no reason to think he’ll be any better running for Senate. The GOP keeps the seat, and chances are, gets a more conservative senator.