Go ahead and celebrate, Sen.-elect Tim Kaine.

AP Photo/Matt Rourke

emocrat 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:

CBS calls VA for Tim Kaine. "Wow" overheard in the Boston press file.

— Molly Ball (@mollyesque) November 7, 2012

Oregon Sen. Jeff Merkley is pleased:

Huge congrats to Virginia's next Senator, Tim Kaine. Looking forward to working with him to reform the filibuster!

— Jeff Merkley (@JeffMerkley) November 7, 2012

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

Okay, George Allen. Time for a new career. RT @timepolitics: CBS News projects Tim Kaine the winner of Virginia senate race.

— daveweigel (@daveweigel) November 7, 2012

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

With CBS calling Virginia for Tim Kaine, @fivethirtyeight is 10-0 by my count on Senate races.

— Bill Barnwell (@billbarnwell) November 7, 2012