The 50 - 44 win would have seemed unlikely to many republicans months ago, but a gaffe during the final televised Senate debate over Mourdock's views on abortion tipped the scales in Donnelly's favor.
"it's a big pick-up, and one the Democrats didn't expect," says Mike Wolf, a professor of political science at IPFW. "They were heading into this election cycle defending 23 states because they had done so well in 2006. They thought they were going to lose a lot of them.
All told, Senate Democrats netted two additional seats in Tuesday's election. Several of the new Democrats are from states that normally favor republicans. Wolf says that could be the beginning of a new, more bi-partisan trend in Senate politics.
"This new class coming in is [made up of] moderates and many of them are from states that are pretty marginal and would normally lean republican," said Wolf. "These are people who are going to be more moderate than the rest of the Democrats so we could see a lot of policy innovation coming from that direction."
On Wednesday, Donnelly told reporters in Indianapolis that he would stay committed to his campaign promise to work with Republicans in Washington.