Now that filings are complete, let's take a look at the field of play in the state Senate.

We're keeping an eye on 11 races as election season begins. Republicans hold five, Democrats hold six. Two are open seats, nine will be defended by incumbents. The other 13 seats are unlikely to become competitive because of the partisan tilt of the district, the presence of a strong incumbent, or both. As campaigns develop, we will revisit the list from time to time.

Today we'll review the GOP seats that are likeliest to be competitive in the fall.

8th district: If this were an open seat, the Democratic candidate would be favored in this district, which includes towns in Cheshire and Sullivan counties. In 2004, George Bush carried 47 percent of the vote, Gov. Craig Benson 46 percent. Incumbent Bob Odell, seeking his fourth term, faces state Rep. Jay Phinizy. Odell has twice cruised to re-election, the last time in a very, very Democratic year.

11th district: State Sen. Peter Bragdon, now seeking his third term in office, won this seat by a 450-vote margin four years ago. The 11th has an ever so slight Republican tilt; Bush carried 50 percent of the vote four years ago, Benson 51 percent. In a tough year for Republican incumbents, the Milford resident defeated lightly funded (yet irrepressible) Democratic activist Howard Morse in 2006 by a 54-46 margin. This time state Rep. Steve Spratt, who represents the western part of the district, will challenge the incumbent.

1st district: John Gallus is another member of the freshman class of 2002. Like Odell, he won re-election easily in 2004 and 2006. State Rep. Martha McLeod may pose a tougher challenge, but her base in Franconia is small. Gallus's home is the city of Berlin. Four years ago, Bush won 49 percent of the vote here, Benson 48 percent. If Barack Obama continues to have difficulties with white, working-class voters, there may be ramifications downballot here.

16th district: On Election Day two years ago, I thought the Democrats would win five seats. If you had asked me for a sixth, I would have guessed Bob Backus would pull off the upset against Republican leader Ted Gatsas. (The Democrats did pick up that sixth seat, to Ray Buckley's glee, but it was in the 4th district.) The Democratic challenger's tough, well-financed campaign fell short by a margin of just 314 votes. Backus defeated Gatsas in their home city of Manchester, as well as the town of Bow. The incumbent had to rely on core Republican towns Candia and Hooksett to pull him through. All that said, Bush carried this district with 54 percent of the vote four years ago; Benson did, too, with 51 percent. District voters should expect lots of mail from Backus, and Gatsas signs that require Manchester Airport to redirect air traffic.

And here's a wild card to watch:

3rd district: In Buckley's dreams, you say? Could be, could be. But hey, it's an open seat now that incumbent Joe Kenney is off to face Gov. Lynch. And Carroll County is only a pale imitation of its former Republican self; Bush won 53 percent of the vote here four years ago, though Benson won 57 percent.

Next up: Competitive Democratic seats.

Dante Scala teaches American politics at the University of New Hampshire and blogs at Graniteprof.