Conservative billionaire Charles Koch and his family have maxed out to Iowa state Senate candidate Joni Ernst (R), a sign of the Koch brothers' particular interest in helping her campaign.
She's just the second candidate all four Kochs have maxed out to this year. Sen. Tim Scott (R-S.C.) is the other.
The donations aren't a shock. Americans for Prosperity, the big-spending conservative group partly bankrolled by Charles and his brother David, has already been on the air in Iowa pounding Ernst's opponent, Rep. Bruce Braley (D-Iowa).
The race for retiring Sen. Tom Harkin's (D-Iowa) seat has emerged as a marquee Senate battle, and recent polls show a close fight.
Democrats have been looking to tie Ernst to the billionaires and their financial interests, but her campaign pointed fingers back at Braley's donors, too.
"The real story for Iowans are the countless liberal extremists bankrolling Bruce Braley's campaign," said Ernst spokesman Derek Flowers.
—This post was updated at 5:32 p.m.