DENVER -

Colorado Republicans are taking aim at a new requirement that every registered voter get a ballot by mail.

Two Republican state senators are proposing bills that would let voters opt out of receiving a ballot by mail, and allow anyone to challenge the validity of ballots cast by mail.

The bills are scheduled for a hearing and vote in a Senate committee Monday afternoon.

Last year, Democrats passed an election-law overhaul that, among other things, allowed Election Day voter registration and required mail ballots for every registered voter. Voters can still vote in person.

Republicans have been critical of the election law changes and have pledged to modify or undo them.