Dustin here with more on Elena's post, including a table with all the approval data.
12 of the 25 governors we've polled on are leaving office, most because of term limits. It looks like legislative dictate picked the right time for 8 of them to retire--they each have net negative approval ratings, as do Jim Gibbons, who lost his primary to Brian Sandoval in Nevada, and Bill Ritter, who wisely chose to not run for another term in Colorado.
The impact on the elections is pretty clear, and the big picture looks better for Republicans than Democrats, though there are a few silver linings for Obama's party.
Of the 18 governors in the red, 11 are Democrats. 5 of them are leaving office, but 5 are up for election this year. Of those, only Massachusetts' Deval Patrick is favored to survive, though narrowly in a three-way race, with Illinois' Pat Quinn and Ohio's Ted Strickland on the precipice of defeat and Iowa's Chet Culver a sure loser. As Tom has noted, the Midwest is not looking good for Democrats this year.
While there are only two Republican governors with negative margins who are up for re-election, they both are facing close races and could lose. They are both in the Southwest, and could hurt if Hispanics continue moving toward Democrats in that region, as our polls have suggested is happening. Our April poll in Arizona had Jan Brewer down three to Terry Goddard just after the immigration bill had passed; we haven't yet gone back into that state. In June, we made a stir by showing Bill White tied with Rick Perry in Texas.
The Southwest's blue trend of the last few cycles is also seen in the fact that of the 5 Democratic governors in the negative who are leaving their seats open, three are favored to flip to the GOP (Michigan, Wisconsin, and Pennsylvania), all in traditionally blue but occasionally competitive Great Lakes states. The two close races that are looking good for Democrats are in Mountain swing states New Mexico and Colorado (the latter especially so after Tom Tancredo's entry and Scott McInnis' plagiarism troubles).
Of the five Republican open seats, only one is favored to switch parties--California--though our latest poll this week showed Meg Whitman and her money bags closing in on ex-governor Jerry Brown. Alabama, Nevada, and South Carolina all lean GOP. Georgia could be a tight race; though the GOP picture has changed, our February poll showed another former head of state, Roy Barnes, leading all comers by small margins.
An interesting note: Elena focused on how many massively unpopular governors there are, but of the four states where the governor is the most popular figure of the four (Obama, the two senators, and the governor), three are Democrats--Mike Beebe of Arkansas, who is the most popular; John Lynch of New Hampshire; and Steve Beshear of Kentucky, a deeply red state at the federal level but one with a history of Democratic governors and an ostensibly Democratic registration advantage.
The data is here.