We need a system of governance where an elected politician’s first loyalty lies with the people, not a political party.
Having given my plug, Mr. Romney has different constituents than most Republicans: his Mormon base in Utah. He would have offended a lot of them had he gone with the acquittal.
He has another 4.5 years in the Senate so there isn’t much the R Party can really do about his lack of fealty. Things change fast in politics, and his stand will position him for better things when they do change.