Minnesota Republicans have a big obstacle to some of their policy goals in Governor Mark Dayton, but they may try a potent workaround in the 2012 legislative session, which starts Tuesday. The GOP already succeeded in setting a statewide vote on whether to ban gay marriage via the state Constitution. Now they’re considering others. One would require voters to show a photo ID; one would require a supermajority of state lawmakers to raise taxes, and one would make membership in labor unions voluntary. Dayton says it’s a misuse of a lawmaking process that should include input from both the executive and legislative branches. But he can’t stop it because Minnesota governors can’t veto proposed constitutional amendments.