Mitt Romney
Mitt Romney was criticized by Texas Gov. Rick Perry and conservatives for refusing to stake a position on Ohio's anti-union law, which is headed for repeal through a voter referendum. Reuters

Mitt Romney refused to give his full support to Ohio's Senate Bill 5 Tuesday, a ballot issue that opponents say seeks to destroy public employees unions and supporters say is neccesary to bring down the cost of government.

I'm not speaking about the particular ballot issues, Romney told a crowd outside a call center, according to CBS News. Those are up to the people of Ohio. But I certainly support the effort of the governor to rein in the scale of government.

This represented a bit of a shift for Romney, who had previously come out in strong support of Ohio Gov. John Kasich and of Senate Bill 5.

My friends in Ohio are fighting to defend crucial reforms that the state has put in place to limit the power of union bosses and keep taxes low, Romney wrote on Facebook last summer, according to Politico. I stand with John R. Kasich and Ohio's leaders as they take on this important fight to get control of government spending. Please visit www.BetterOhio.org for more information.

Senate Bill 5, passed by the Republican controlled Ohio legislature earlier this year, would weaken the collective bargaining power of unions for public employees including police, fire fighters and teachers, according to a report from the Columbus Dispatch. It was added to the ballot as Issue 2 this summer and has sparked passion from both sides throughout Ohio.

Following Romney's statement, rival Rick Perry came out in strong support of Kasich and the bill.

As a true conservative, I stand with Gov. Kasich in promoting S.B.5 for fiscal responsibility and job creation in Ohio, Perry said in a statement to CNN. Gov. Kasich and the Republican leadership of Ohio are to be commended for their efforts.

He later tweeted more support.

Ohio Gov John Kasich is right to protect and create jobs, the tweet read. Stand with him to fight union excesses. Help make Ohio more competitive!!

Senate Bill 5 is currently trailing by 25 percent in the Quinnipiac poll, according to the Dispatch.