Top Illinois Republicans are requesting that the State Board of Elections grant an extension to a group gathering signatures to take the political map-making process away from lawmakers.

The group submitted more than 500,000 signatures to the Board of Elections last month. But executive director Rupert Borgsmiller says less than half of a 5 percent sample of signatures was valid.

The proposed constitutional amendment would give mapmaking responsibilities to an independent commission.

The group needs nearly 300,000 valid signatures to put the proposal on the ballot.

The effort also faces a court challenge.