There are 15 interesting races, 14 of which are for Republican-held seats.
Clear Democratic Leads (3)
New Hampshire - Except for two outliers from disgraced (by their record in the primaries this cycle) polling firm ARG, all of the polls of this race show Jeanne Shaheen (D) holding a substantial lead over John Sununu (R). On 2/11/08, the Granite State Poll put her lead at 54%-37%, while Rasmussen has a 2/13/08 poll that shows her up 49%-41%.
New Mexico - Tom Udall (D) leads Heather Wilson (R) 58%-30%, and Steve Pearce (R) 53%-31% in NMSU's 2/11/08 poll. He consistently out-polls both GOP congresspeople by wide margins.
Virginia - Mark Warner (D) leads Jim Gilmore (R) 53%-38% in Rasmussen's poll of 1/3/08. Those figures are virtually unchanged from Rasmussen's 10/30/07 poll and reflect the general consensus that Warner has a massive lead.
Polling Toss-Ups (4)
Alaska - It feels a little presumptive to label this race a toss-up, especially since the presumptive challenger, Anchorage Mayor Mark Begich, has yet to declare his candidacy. Still, Research 2000 showed Begich (D) leading Ted Stevens (R) 47%-41% on 12/3/07-12/6/07.
Colorado - Polling in this race has been consistently close. Bob Schaffer (R) had a statistically insignificant lead of 44%-43% over Mark Udall (D) in Rasmussen's 2/11/08 poll.
Louisiana - SurveyUSA released the only public poll for this race on 12/13/07. At the time, Mary Landrieu (D) led John Kennedy (R) 46%-42%.
Minnesota - Al Franken (D) and, to a lesser degree, his primary competitor Mike Ciresi (D), has closed the gap on Norm Coleman (R). Minnesota Public Radio has the most recent poll, which showed Franken leading 43%-40%, while Ciresi trailed 43%-38% (1/29/08).
Races That Still Need Some Work (8)
Idaho - Larry LaRocco (D) is the best candidate we could have hoped for in a state like Idaho (OK, there's Cecil Andrus, but he's 76), but he's not yet in striking range of Jim Risch (R), trailing him 48%-34% in Myers Research's poll of 11/13/07-11/19/07.
Kentucky - Mitch McConnell (R) will face one of two wealthy businessmen, Greg Fischer (D) and Bruce Lunsford (D). There is no polling (that I'm aware of) on either match-up, but I think we can assume that McConnell will start with an edge over his challengers.
Maine - Susan Collins (R) maintains a stubborn lead over Tom Allen (D). SurveyUSA's 11/5/07 poll is representative in pegging her lead at 55%-38%.
Mississippi - We have no reliable polling on this race, but I'm guessing that Roger Wicker (R) has a modest lead over Ronnie Musgrove (D) and a more comfortable margin over Ronnie Shows (D).
North Carolina - Elizabeth Dole (R) is vulnerable, but holds a substantial early lead over his two potential opponents, Kay Hagan (D) and Jim Neal (D). Rasmussen's 12/26/07 poll put her lead at 55%-35% over Hagan.
Oklahoma - It might be that the only reason this race is on the list is because I love Andrew Rice's (D) biography. Still, Tom Coburn's 2004 race was kinda close, so maybe there's hope. Anyway, Jim Inhofe (R) led Rice 60%-28% in Tulsa World's 12/16/07-12/19/07 poll.
Oregon - Aw, crap, those Novick-ites are gonna come back, aren't they? Anyway, SurveyUSA's 11/5/07 poll showed Gordon Smith (R) leading Jeff Merkley (D) 48%-39%, and Steve Novick (D) 45%-39%. However, those polls did not include independent candidate John Frohnmayer, who I expect to take more Democratic votes than Smith votes.
Texas - Since Mikal Watts' withdrawal, Rick Noriega (D) has just about locked up the Democratic nomination. Now it's time to get to work, given that Research 2000's 9/24/07-9/26/07 poll showed him trailing John Cornyn (R) 51%-35% (Rasmussen's numbers from September '07 were similar).
We just need three races to move up into the toss-up category for a 60-seat majority to be a realistic possibility.