WASHINGTON — A group backed by the Koch organization is praising North Dakota Democrat Heidi Heitkamp — a move that could boost the re-election campaign of one of Republicans' top Senate targets to beat in November. 

The group, Americans for Prosperity, has released a digital advertisement thanking Heitkamp for her vote to roll back a portion of the Dodd-Frank banking regulation bill.

The praise by the Koch-affiliated group, which has traditionally worked to elect Republicans to office, comes as Heitkamp is running against Republican Rep. Kevin Cramer in one of the reddest states in the country.

The organization won’t reveal how much money they are spending, but the ad says, “Thank you, Sen. Heitkamp for giving Main Street relief.”

“It doesn’t mean any kind of endorsement in a political campaign, but it is a genuine thank you,” Tim Phillips, president of AFP, said in a phone interview.

Cramer has complained that some on the White House are not doing enough to support him against Heitkamp.

Heitkamp has been running in North Dakota as a senator who can be a check on President Trump but can also work with him too. She was the only Democrat invited to the White House last week for the bill signing of the Regulatory Relief and Consumer Protection Act, which will remove regulations on community and regional banks (and some large banks) implemented in the aftermath of the financial crisis in the Dodd-Frank banking bill.

"Heidi got results for rural North Dakota families and businesses who depend on relationship lending because she is and has always been focused on putting partisan politics aside to deliver for North Dakotans — and that's where her focus will remain,” Julia Krieger, Heitkamp’s communications director, said of the ad. 

Cramer has recenrtly singled out Marc Short, the White House legislative affairs director who also used to run the Koch political group Freedom Partners.

“Marc Short just seems to be part of the issue and there seems to be an argument between Short and other people in the White House,” Cramer said on local North Dakota radio WDAY’s Rob (re)Port Wednesday.

Cramer, an at-large member of the House, originally passed on a bid for Senate but told NBC News in March that he decided to jump in the race after the third call from Trump pushing him to run.

It's not the first time that the group has broken with its reputation for favoring only GOP members. Last week, AFP launched a "significant" six-figure voter persuasion campaign attacking ten Republicans and seven Democrats, including some House Republicans in tough re-election campaigns and a Republican running for Senate, for backing the government spending bill that added $400 billion in government spending over two years. 

AFP has also attacked Heitkamp in the past, running a $450,000 ad buy in March knocking her for her vote against tax reform.