Heitkamp brought in just shy of $500,000 and has $760,000 in the bank, according to a Federal Election Commission report. Berg raised slightly more than $440,000 and has $1.6 million cash on hand, according to the Fargo Forum. The reports cover the period from April 1 to May 23.

The fundraising figure is good news for Heitkamp, who was buoyed by more than $100,000 from joint fundraisers with other top Senate candidates. She's shown the ability to run a strong campaign in a tough state for Democrats, and while she'll need to pick up the pace to catch up to Berg's cash advantage her ability to keep up with him so far bodes well for her.

The two are in a tight race to replace retiring Sen. Kent Conrad (D-N.D.).

The Hill rates the race a "tossup."