COLUMBUS (AP) — A free-market think tank has launched a billboard campaign advocating what it’s calling "worker voting rights" amid renewed efforts at the Statehouse to make Ohio a right-to-work state.

The Buckeye Institute says the outdoor advertising campaign in Columbus it announced Wednesday is meant to raise awareness among unionized public-sector workers who aren’t given a vote on what labor organization represents them.

Two conservative Republican lawmakers on Tuesday put forth a package of proposed constitutional amendments to limit unions. State Reps. John Becker and Craig Riedel are aiming for the 2020 ballot.

That’s after Republican Gov. John Kasich leaves office.

Ohioans voted overwhelmingly in 2011 to repeal GOP-passed collective bargaining limits. Kasich said after the vote that he wouldn’t support future efforts to limit unions.