Indiana Sen. Joe Donnelly's campaign raised $1.2 million during the last three months of 2017, pushing its war chest up to $5.3 million.
The Democrat is considered one of the most vulnerable 2018 incumbents and is a top Republican target. He will face the winner of the Republican primary, which has drawn two congressmen and a wealthy former state lawmaker as candidates.
Powerful Democrats are helping Donnelly out. Senate Minority Leader Chuck Schumer is hosting a Houston fundraiser for Donnelly and others on Saturday, while former Vice President Joe Biden will soon headline an Indianapolis fundraiser.
Donnelly's campaign says the amount of money raised in a non-election year beat a record set by Republican Sen. Todd Young, who raised $3.5 million in 2015.