After a couple of cycles in which an above-average number of incumbents have lost their seats in Congress, it’s easy to forget that being an incumbent is normally an extremely powerful advantage. Political science models have generally found that the incumbency advantage amounts to 6 to 10 percentage points for a senator, meaning that an incumbent Democrat would be expected to get 56 to 60 percent of the vote in a state where a nonincumbent Democrat would get about 50 percent.
Not all incumbents are created equal, however. Sometimes, the incumbent is so popular that he or she is all but assured of re-election, even in an opposite-colored state or district (e.g., a Republican in a blue state). At other times, like in the case of Jim Bunning of Kentucky last year — or perhaps John Ensign of Nevada this year — the incumbent is so unpopular that he would probably do his party a favor to retire.
Senator Jim Webb, the freshman Democrat from Virginia who announced today that he will not seek another term, is almost certainly not in that category, the hallmark of which is usually that a candidate’s disapproval ratings exceed his approval ratings. Instead, according to a Public Policy Polling survey conducted in November, Mr. Webb’s approval rating was 43 percent, against 37 percent disapproval. Those are not terrific numbers by any means, but they are also not awful — especially for a Public Policy Polling survey since their polls, for whatever reason, tend to show relatively low numbers for incumbents across the board.
Still, Mr. Webb would only have been, at best, a modest favorite against the Republican nominee — most likely George Allen, the man he replaced in the Senate. The Public Policy Polling survey tested Mr. Webb against Mr. Allen and two other prospective Republican candidates, Attorney General Ken Cuccinelli and Lt. Gov. Bill Bolling. It also ran the numbers for two Democrats that might now replace Mr. Webb: former Gov. Tim Kaine, who is now the chairman of the Democratic National Committee, and former Representative Tom Perriello, who narrowly lost his re-election bid but arguably overperformed in a very tough district in a very tough year.
The poll had Mr. Kaine doing no worse, on balance, than Mr. Webb: both had a small lead against Mr. Allen and a slightly larger one against the other Republicans. That isn’t terribly surprising. If you can’t have an incumbent senator, the next best alternative is an incumbent governor, or a former one who retired on reasonably good terms (in Mr. Kaine’s case, because Virginia law prohibits a governor from serving consecutive terms).
Mr. Perriello’s numbers were somewhat worse: he trailed Mr. Allen by 5 points and was essentially tied with the other two Republicans. But he was still highly competitive against them, and some of the difference — especially against Mr. Allen — is probably explained by a comparative lack of name recognition.
A more troubling number for Mr. Perriello is that, of the roughly 50 percent of Virginians who did recognize his name in the poll, more had an unfavorable impression of him. On the other hand, his performance in the Virginia 5th Congressional District races in 2008 and in 2010 (despite his loss) was strong enough to suggest that he could wear reasonably well on voters as he introduced himself to more of them.
On balance, then, this is more of a jab to Democrats than a stomach-punch; Mr. Kaine might not give up anything to Mr. Webb, and Mr. Perriello probably does not give up much.
The greater risk, perhaps, is that candidates like Mr. Kaine and Mr. Perriello take too long to decide whether or not they want to run for Mr. Webb’s seat. Virginia, for a number of reasons, is quite an expensive state to campaign in, and Mr. Allen will be more formidable the more of a head start he gets in fund-raising.