Massachusetts voters are heading to the polls this morning to vote in a Republican presidential primary, joining voters in nine other states who are casting ballots this Super Tuesday, a day that could be an important milestone in the presidential race. Mitt Romney, Newt Gingrich, Rick Santorum, and Ron Paul are squaring off in the latest round of what has been a hard-fought, at times nasty, fight for the GOP nomination. Romney, a former Massachusetts governor who is still a Bay State resident, is poised to do well here today. Political observers are assuming Massachusetts is one of several states Romney will win handily; they’re focusing their attention on other states such as Ohio and Tennessee, where he faces a strong challenge from Santorum.