Wisconsin Gov. Scott Walker (R) won't challenge the petitions calling for him to be recalled from office, his spokeswoman said Monday.

Walker has until the end of the Monday to contest the more than 1 million signatures gathered to force a recall vote, but spokeswoman Ciara Matthews called that an "impossible timeline" for properly verifying the signatures.

Campaigns are allowed 10 days to file challenges under Wisconsin state law. The Monday deadline marks the end of a 20-day extension granted by a judge. An additional two-week extension sought by Walker was turned down.

Walker's opponents, who released their first TV commercial Monday, suggested that any challenge would be fruitless, The New York Times reports:

To force a statewide recall election in Wisconsin, 540,208 legitimate signatures are needed. Organizers of the recall effort, including union members who oppose Mr. Walker’s limits to collective bargaining for public workers, said they had filed papers with about a million names, allowing significant room for flawed or otherwise problematic signatures.

In a statement, the Walker campaign continued to challenge the veracity of the signatures, and called on the state's Government Accountability Board to perform its own review of the petition.

"Since the submission of recall petitions in January, multiple stories have surfaced which point to incidences of fraud and abuse in the recall process," the statement reads. "The Republican Party of Wisconsin has cited examples including addresses of signers turning up as vacant lots and the unquestionably fraudulent signatures of Donald Duck appearing on petitions."

The board has until mid-March to call for a new election.

10 more election stories from beyond the presidential field:

Bob Kerrey To Run For Nebraska Senate [The Washington Post]

Two Republicans End Campaigns Against Minnesota Sen. Amy Klobuchar [NPR]

Scott Walker Hit With First Recall Ad [HuffPost]

Nancy Pelosi Keeps Her Sights On 2012 [Roll Call]

Bob Corker Ahead Of Rivals In Fundraising [Chattanooga Times Free Press]

Redistricted State Senator's Chief Of Staff Loses It On Twitter [HuffPost]

Race To Replace Giffords Shapes Up [USA Today]

Outed Sheriff Paul Babeu Says He's Still In The Race [AP]

Democrats Target Committee Chairmen [The Hill]

Cat Running For Virginia Senate Seat [DCist]

Earlier on HuffPost: