Sen. Heidi Heitkamp faces one of the toughest re-election campaigns in 2018 and represents a deep red state. President Trump won North Dakota with 63% of the vote, his fourth-highest margin in the country. She is, in all likelihood, the most vulnerable Democratic Senator up in 2018.
Sen. Heitkamp was elected to the U.S. Senate in 2012. She won her election against then-Rep. Rick Berg by 2,994 votes, less than 1% of the ballots cast. State Rep. Rick Becker, a self-funder, is the likely GOP nominee.