After a couple of relatively quiet months, the Senate race rankings have undergone a fairly major shakeup, with 15 distinct contests receiving an upgrade or a downgrade based on a combination of local and national circumstances. Most of these changes favor Republicans — 7 of the 10 upgrades (meaning that a party switch is now more likely) were made to Democratic-held seats; 4 of the 5 downgrades were made to Republican-held seats. While there are still plenty of opportunities for the Democrats in the Senate, I believe that the Republicans are now slightly more likely to gain seats than to lose them, potentially threatening the Democrats’ supposed filibuster-proof majority.
Races are ranked in order of their likelihood of changing parties (by November 2010, accounting for all factors such as potential retirements, primary challenges, and so forth).
Likelihood of party switch has increased since last month‘s rankings.
Likelihood of party switch has decreased since last month.
1. 
Missouri (R-Open)
We’re waiting to see whether Robin Carnahan’s numbers have been weakened any by the national tide having turned somewhat against the Democrats. Meanwhile, Roy Blunt had vastly improved fundraising numbers in the second quarter. Still, this is the sort of cycle that — even if it tends to work against Democrats, may also tend to favor outsider candidates, and Blunt — a seven-term Congressmen and former Majority Whip — is not exactly the freshest of faces. I’m hedging a bit by giving Missouri a down arrow but nevertheless allowing it to retain the top slot on our list for the time being. Really, you could argue for almost any ordering of the top five or so races.
2. New Hampshire (R-Open)
Kelly Ayotte, on the other hand, the Republican Attorney General of New Hampshire, is a relatively fresher face, although some New Hampshire observers I’ve spoken with wonder whether she might ultimately be too green to run a top-notch campaign. Still, another poll has come out showing Ayotte in a dead head with Democratic nominee Paul Hodes. She certainly gives the Republicans far better chances to retain Judd Gregg’s seat than a retread like Charlie Bass or John Sununu might have.
3. Connecticut (D-Dodd)
New Quinnipiac polling doesn’t show Chris Dodd’s situation improving any, but there remain a lot of contingencies in this contest: is Rob Simmons a safe bet to win the Republican primary when he’s likely to face a couple very well-financed challengers? Is Dodd himself in the clear from a primary challenge? How will Dodd’s diagnosis of prostate cancer affect the dynamics of the race? For the time being, it would be foolish to characterize this race is anything other than a toss-up.
4. 
Nevada (Sr.) (D-Reid)
Harry Reid’s approval numbers have been in the dumps for some time now, but the argument against ranking this race more highly was that the Republicans lacked credible challengers. But now it appears that it might not matter: (relative) no-name Republicans are beating him. Reid currently has more than $7 million in cash-on-hand and Nevada is something of a machine state, so this is an easier pickup on paper than it will be in practice. Still, this is a very, very vulnerable slot for the Democrats.
5. Ohio (R-Open)
Rob Portman, as we anticipated, has now accelerated past his Democratic rivals in terms of fundraising. Still, although an anti-Bush message is likely to be a tired and losing one for Democrats in most instances in 2010, it may carry more weight when employed against Bush’s former budget director, and Portman has not yet pulled ahead of the Democrats in the polls.
6. 
Kentucky (R-Open)
Jim Bunning, after much deliberation, will in fact retire. Unless he pulls a Favre, this is a big favor for Republicans. They are, however, hardly out of the woods in Kentucky, as the two leading Democratic candidates continue to poll competitively against the two leading Republicans. One dynamic to watch for in Kentucky is that Rand Paul, son of Ron Paul, will probably put the Republicans at a disadvantage if he defeats Trey Grayson for the party’s nomination. Kentucky is arguably among the worst environments for a libertarian candidate in the country: socially conservative but somewhat more liberal economically, the exact opposite of the libertarian sweet spot.
7. 
Colorado (D-Bennet)
An underwhelming field all around in Colorado; nominal incumbent Michael Bennet has a net-negative approval rating, but his most likely Republican opponents aren’t liked any better. A race like this is likely to be determined by national factors, rather than local ones, and right now those factors are looking much improved for Republicans, especially in a state where Obama’s approval ratings have been poor relative to his election-day performance.
8. 
Illinois (D-Burris)
A Rasmussen poll shows Mark Kirk with a three-point lead over Democrat Alexi Giannoulias; on the other hand, that poll was based on a likely-voter sample in which Barack Obama had just 56 percent approval in his home state. At the end of the day, both parties are fielding fairly strong candidates here and I expect the race to gravitate back toward the partisan ID split in Illinois, which ordinarily favors Democrats. But Kirk is entirely capable of prevailing if Giannoulias runs a poor campaign or Republicans are having a good night nationwide.
9. Delaware (D-Open)
We’re continuing to wait on U.S. Rep. Mike Castle to make a decision about whether to enter on Republicans’ behalves. If he doesn’t make that decision fairly soon, this race might warrant a slight demotion. Then again, since Castle has been in public office since 1981 and reprsents the entire state, he won’t necessarily need a lot of time and money to introduce himself to Delaware’s voters, making a late start more viable.
10. 
Pennsylvania (D-Specter)
While Democrats are busy fighting a primary battle, likely Republican nominee Pat Toomey, who was one once of the three or four most conservative members of the House, is cleverly and somewhat disingenuously trying to position himself as a moderate, having advocated, among other things, for Sonia Sotomayor’s confirmation to the U.S. Supreme Court. I’d expect Democrats to win over some votes by pushing back on Toomey’s track record once they’ve picked a nominee, although as I suggested before, Arlen Specter’s own inconsistencies might make him less capable of doing so than Joe Sestak. Specter, indeed, has become a lighting rod for criticism from virtually all corners of the political spectrum, although I continue to have trouble believing that either he or Sestak would ultimately be an underdog against Toomey.
11. North Carolina (R-Burr)
Republican Richard Burr has unusually low name recognition for an incumbent, and a lot of the voters that know him don’t particularly like him. The question, as Public Policy Polling’s Tom Jensen suggests, may be whether 2010 is more of an anti-incumbent year — in which case Burr is in some trouble — or merely an anti-Democratic year.
12. 
Arkansas (D-Lincoln)
A recent poll has Blanche Lincoln’s approval down to 49 percent. The poll was conducted by a Republican strategy firm and warrants caution for that reason, but I don’t have trouble believing that voters have begun to grow wary of Lincoln, who has had a difficult time articulating her positions on issues like health care and EFCA. The saving grace for Lincoln is that Republican opposition in this race is poorly organized. If I were the NRSC, I might put something of a bounty on Lincoln’s head and see if I couldn’t come up with a more capable challenger.
13. 
Texas (R-Open?)
While in Pittsburgh for Netroots Nation, I had a chance to speak briefly with Houston Mayor Bill White at a luncheon, who will run for Senate if, as anticipated, Kay Bailey Hutchison eventually vacates her Senate seat to concentrate on her gubernatorial bid. White is a sharp guy in an unmistkably Texan, slow-moving sort of way. The basic mathematical argument he presents is reasonably compelling: although Republicans have a very slight partisan identification advantage in Texas, White is rather popular in the Houston area, where he was re-elected in his last two terms with 90 and 86 percent of the vote, and the Houston media market represents about one-quarter of Texas’ electorate. Although Texas would hold a “jungle primary” in the event of a speical election, White anticipates that the race would quickly boil down to a two-candidate affair: himself and whomever Rick Perry nominates to be Hutchison’s replacement — likely a very conservative Republican. White would therefore run as a moderate — perhaps almost as a quasi-independent — which might impede fundraising and enthusiasm among national Democrats but is something he could live with since he’s raised plenty of money on his own. It’s a pretty good story; the question is whether White might be running into too much of a national headwind, especially in a special election environment in which turnout is liable to be low.
14. 
Louisiana (R-Vitter)
Democrat Charlie Melancon is in a little bit of a pickle. Having voted against the Democrats’ health care package in committee, he may not receive much financial support from national Democrats — a bit of a problem against an incumbent like David Vitter who has $3.2 million in cash-on-hand. Louisiana has become a tough state for Democrats and 2010 is likely to be a reasonably tough year; although he should be competitive enough to keep the race interesting, ultimately I’d have to rate Vitter as the fairly heavy favorite.
15. 
North Dakota (D-Dorgan)
Governor John Hoeven is in no apparent hurry to decide whether to challenge Byron Dorgan for his Senate seat. As I suggested last month, this feels like a bluff on Hoeven’s behalf, designed to push the influential Dorgan toward more conservative stances on issues like health care and energy. With that said, the reason I’ve thought this is probably a bluff is Hoeven had looked like he’d been an underdog to Dorgan, and most sitting governors won’t give up their seats to run a race that they’d probably lose. But if the national environment becomes favorable enough for Republicans, Hoeven might begin to take his Seante prospects more seriously.
16. 
Iowa (R-Grassley)
Chuck Grassley’s position at the eye of the health care hurricane could leave him vulnerable on both flanks. A primary challenge, if successful, could turn this into an open seat contest. Meanwhile, IA-1 Congressman Bruce Braley is now contemplating taking on Grassley in the general election. Grassley remains well-liked by Iowa voters and has a lot of goodwill to burn through, but this one is starting to get interesting.
17. Florida (R-Open)
There’s the possibility that Charlie Crist will get himself into a little bit of trouble in picking a replacement for Mel Martinez, but as we’ve suggested repeatedly, the Democratic opponents in this race are not especially strong statewide candidates and appear to be significant underdogs against both Crist and the other GOP hopeful, Marco Rubio.
18. 
New York (Jr.) (D-Gillibrand)
With Carolyn Maloney unlikely to challenge her, Kirsten Gillibrand should now have plenty of time to raise money to hedge against a late entry by George Pataki or Rudy Giuliani.
19. 
California (D-Boxer)
A Rasmussen poll has Carly Fiorina within four points of Barbara Boxer, but other surveys do not have the race being nearly as competitive. Considering Fiorina’s underwhelming performance as a spokesman for the McCain campaign, I expect her to be mostly an annoyance to both Democrats and Republicans, who have a better opportunity with Meg Whitman in the governor race.
20. Georgia (R-Isakson)
21. Arizona (R-McCain)
22. Hawaii (D-Inoyue)
23. Wisconsin (D-Feingold)
24. 
Nevada (Jr.) (R-Ensign?)
We had inserted this race on our list last month on speculation that John Ensign’s adultery scandal might force him into early retirement. Although Ensign is in a great deal of trouble for 2012, he seems to have limped through his scandal in strong enough position to at least keep his seat for the time being. Unless there are further revelations, we will consider de-listing this race next month.
25. 
South Carolina (R-DeMint)
Jim DeMint may face a Democratic challenger after all in the form of State Sen. Brad Hutto. Although there are some vague parallels here to Kay Hagan’s successful insurgent bid last year against Elizabeth Dole in North Carolina, 2010 is likely to be a far less favorable cycle for the Democrats and their infrastructure in South Carolina is notoriously poor. DeMint’s approval rating has not been tested for a long time — the most recent poll is from November, 2006 when he came in at a 51/36 approve — so it’s worth waiting to see if someone polls this race. But for the time being, it looks like no better than a long shot.
26. Oklahoma (R-Coburn)
27. Alaska (R-Murkowski)
28. Kansas (R-Open)
29. Maryland (D-Mikulski)
30. Washington (D-Murray)
31. Alabama (R-Shelby)
32. South Dakota (R-Thune)
33. Indiana (D-Bayh)
34. Vermont (D-Leahy)
35. Oregon (D-Wyden)
36. Utah (R-Bennett)
37. New York (Sr.) (D-Schumer)
38. Idaho (R-Crapo)