In looking at the 2010 Senate picture, it strikes me that in a neutral-to-Dem-favorable environment and with decent recruiting, the party could net 5 or more seats for the third straight cycle. This has not happened since the Democrats netted 8, 12, 10.5, and 7 seats from 1930-36, moving the chamber from a 56-39-1 Republican majority to a 75-17-4 Democratic one. In 2010, there are 19 (possibly 20) GOP seats up and 17 Dems. And the differences in the lists are striking.
Dems
Leahy (VT)
Dodd (CT)
Schumer (NY)
Gillibrand (NY)
Kaufman (DE)
Mikulski (MD)
Lincoln (AR)
Bayh (IN)
Burris (IL)
Feingold (WI)
Dorgan (ND)
Bennet (CO)
Reid (NV)
Boxer (CA)
Wyden (OR)
Murray (WA)
Inouye (HI)
Note that there are no open seats as of yet, just as Dems had no open seats in 2008. The likeliest retiree, Hawaii's Dan Inouye, says he's running again. Assuming that statement remains operative, that leaves only Barbara Mikulski of Maryland and perhaps Chris Dodd of Connecticut (as well as Delaware appointee Ted Kaufman and Illinois appointee Roland Burris) as potential retirements. Odds are fairly decent that only Kaufman actually retires.
Who in this list looks vulnerable? Well, I would say that Leahy, Schumer, Mikulski, Bayh, Wyden, Murray and Inouye are essentially invincible. Dodd, Feingold and Boxer all look very strong. So does Lincoln, despite representing a state trending red nationally; the GOP has no statewide bench and her colleauge Mark Pryor ran unopposed in 2008. Dorgan, too, will likely coast again unless the GOP can get Gov. Hoeven into the race.
So, who does that leave? Harry Reid and the four appointees (sounds like a band). Reid has been a likely top target, and his leadership decisions such as they are have not won him any points with anyone. But Nevada just shockingly went for Obama by 12 points on the backs of a far more Latino electorate. That bodes well for Reid, as does the fact that of his two most likely/strongest opponents, one just got indicted and the other lost his House seat.
Three of the four appointees come from solidly blue states. Illinois has elected exactly one GOP senator in the last 30 years; Delaware likewise has elected just one--and that incumbent was first elected in 1970; and New York has been solid blue since it ousted Al D'Amato in 1998. The Delaware seat is likely going to be a Beau Biden coronation, and the New York seat may well see more action in a primary than a general. Barring a third party run from the left by a NYC pol, Gillibrand looks like an exceptionally strong Dem statewide candidate.
So that leaves Burris and Bennet. Burris has some issues surrounding how he got appointed to the Senate, which I would expect to be largely a non-issue by 2010. But he also has been out of politics for a long time and could theoretically be vulnerable, especially if softened up in a nasty primary (or his opponent could have a tough road if he or she takes Burris out in an ugly primary). Bennet is untested electorally and faces a swing state electorate. But that's it.
GOPers
Gregg (NH)
Specter (PA)
Burr (NC)
DeMint (SC)
Isakson (GA)
OPEN (FL)
Shelby (AL)
Bunning (KY)
Vitter (LA)
Coburn (OK)
OPEN (OH)
Grassley (IA)
OPEN (MO)
OPEN (KS)
Thune (SD)
Crapo (ID)
Bennett (UT)
McCain (AZ)
Murkowski (AK)
Unlike the Dems, the GOP has 4 open seats and counting--Specter, Shelby, Bunning and Grassley have all been linked to retirement rumors. 3 of the 4 current open seats are in classic swing states. And this does not even include the potential special election in Texas if and when Sen. Hutchison resigns to pursue the governorship, pitting an appointee (or someone who beat the appointee in a primary) against the biggest names the TX Dems have.
In addition, the GOP has an exceptionally large 2004 freshman class up for reelection for the first time. Seven of these Senators appear in the list above. Sure, that group includes DeMint, Isakson, and Coburn, who are likely safe--and Murkowski probably is, too--but it also includes potential targets Burr, Vitter and Thune.
Finally, Bunning is exceptionally weak (to the point where the GOP would rather he retired); and Gregg and Specter are facing electorates that have moved away from them ideologically and state Democratic parties that have gotten exponentially strong since the last time they ran.
So, who of the 19 looks safe? DeMint, Isakson, Shelby, Coburn, Grassley, Crapo, Bennett, McCain and the Kansas open seat (assuming Sebelius stays out). And probably Murkowski. And possibly Thune. Which leaves 8 more seats at which the Dems have a very solid shot (the Florida, Ohio and Missouri open seats; freshmen Burr and Vitter; and veterans Gregg, Specter and Bunning). Sure, it may be a good GOP year, and they may win all the close ones (like they did in 2004 and like the Dems did in 1998) to pick up a few seats. But they could also lose 6-8 for the third cycle in a row, which is amazing and would give the Dem majority numbers it has not had since the 1960s.