Heitkamp finishes off the ad, telling viewers she approves the message "because I'll work to strengthen Medicare, not destroy it."

The new spot adds to an already heavy barrage from both sides, further underscoring the fierce competitiveness of the race for the seat.


Heitkamp's ad is out just a day following one in a similar format released by the Democratic Senatorial Campaign Committee — with an average North Dakotan addressing the camera — that frames Heitkamp as independent compared to Berg's support of the GOP's policies. And Berg is up this week with an ad tying Heitkamp to President Obama.

The constant back-and-forth is because the race remains close — though Berg has led in most polls, Democrats believe Heitkamp is one of their best options for keeping control of the Senate. Republicans, however, see the seat as integral to gaining the majority, and will continue their fierce fight for it.