Efforts to recall Republican Wis. Gov. Scott Walker over his moves to curb collective bargaining rights are scheduled to begin at 12:01 a.m. Tuesday.

Events are planned state-wide to begin collecting the more than 540,000 approved signatures needed to force a recall election that could take place as soon as this spring. Supporters have until Jan. 17 to collect the signatures.

Leading the recall campaign is United Wisconsin, a political action committee. Vice Chair Lynn Freeman said the organization is aiming for more than 800,000 signatures.

“We intend to have enough signatures, all of them legitimate, that there’s no question that we’ve met the threshold of the over 540,000 that’s needed when those signatures are approved,” said Freeman.

The efforts come after Walker pushed through a controversial law that effectively ended collective bargaining rights for most public workers earlier this year.