Story highlights Rep. Kevin Cramer could challenge Heidi Heitkamp in next year's midterms

Other Republicans want Tom Campbell to run instead

(CNN) Top Republicans in Washington are privately sending this message to a GOP congressman once viewed as a top recruit in North Dakota: Don't run against Sen. Heidi Heitkamp next year.

Senior Senate GOP officials have grown concerned that Rep. Kevin Cramer's penchant for controversial remarks could damage their chances at one of the party's most prized opportunities to pickup the crucial seat occupied by Heitkamp, a rare Democratic statewide officeholder in the conservative state. Cramer's latest remark: Defending Sean Spicer this week in the aftermath of the White House spokesman's widely condemned comments about Adolf Hitler and the Holocaust.

Behind the scenes, there's a growing GOP push to woo a wealthy North Dakota state senator, Tom Campbell, who has the resources to largely self-fund a campaign against Heitkamp, according to multiple sources familiar with the matter.

Campbell is taking a series of steps to mount a challenge, putting together an organization with the resources that will let him run for a statewide office next year, according to Chip Englander, a political adviser to the state senator. Campbell "definitely" will run for either the House seat now occupied by Cramer or for the Senate seat next year, Englander said.

"He can even the score on Day 1," Englander said, suggesting Campbell could drop roughly $2 million into the campaign to immediately eliminate Heitkamp's financial advantage. He said Campbell would raise some money also if he mounts a run.

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