MADISON, Wis. (AP) -- Three recall elections for Democratic state senators have been certified, starting the clock for Republicans to officially declare their candidacies and for the filing of court challenges.

Six Republican senators also face recall elections, all of which will be held in July and August in the largest concerted effort to remove incumbents from office during their terms in Wisconsin history.

The Government Accountability Board certified the recalls for the Democrats on Friday. Candidates wishing to run against them have until June 21 to file with the board. The deadline for candidates running against the six Republicans is Tuesday.

The incumbents do not have to file to run and all of them plan on defending their seats.