The drive to legalize same-sex marriage in Minnesota has received a boost, as a Republican state senator prepares to cross party lines and join the effort. "At this point, I am concerned about doing the right thing," state Sen. Branden Petersen (R) told the Minneapolis Star Tribune. "I have a certain amount of peace about that, and I will let the chips fall where they may."If Petersen signs on to the same-sex marriage bill expected to be introduced this week, he would be the first Republican lawmaker to do so.