Democrat Tim Kaine has defeated Republican challenger George Allen in the closely-watched Virginia Senate race. Allen has reportedly already conceded.

Kaine, who is both a former Virginia governor and a former head of the Democratic National Committee, ran on a record of bipartisan accomplishments and a commitment to protecting Medicare and Social Security. Meanwhile, this is the second consecutive senatorial defeat for George Allen, who had been widely projected to wallop Democrat Jim Webb in 2006 — until his campaign was derailed by controversy over his use of the word "macaca" to describe an Indian-American staffer on the Webb campaign. Webb is retiring after a single term, and this year's Virginia Senate race has been under particularly close scrutiny because many analysts believe Republicans needed a victory in Virginia to gain a majority in the Senate. It now looks like the GOP will fall well short of that goal

Here, early reactions to Kaine's victory:

The Atlantic's Molly Ball says that even the press is surprised:

Oregon Sen. Jeff Merkley is pleased:

Slate's Dave Weigel thinks Allen should quit while he's behind:

Grantland's Bill Barnwell says Kaine's victory is also good news for stats guru Nate Silver: