Transcript for Heidi Heitkamp says she has 'no regrets' voting against Kavanaugh
Next tonight, one weekend left of the political ads. Tonight, the democratic senators in states where Donald Trump won handily, many of them siding with the president with key issues. But one telling us breaking with him on Brett Kavanaugh may cost her her job. Here's Mary Bruce. Reporter: From West Virginia, to North Dakota, and Missouri, in the states won by Donald Trump, senate Democrats are now fighting to hold on to their jobs. For Joe Manchin, that means walking a fine line. I stand up and support him when it's good for west Virginia. And when it's not, I stand up to him. Reporter: In Missouri, Claire Mccaskill is eager to show she's willing to take on her fellow Democrats. Just listen to her closing ad. Claire is not afraid to stand up against her own party. Yup. And Claire is not one of those crazy Democrats. Reporter: But in north Dakota, a state trump won by a whopping 36 points, Heidi Heitkamp broke with the president on a key issue just one month before the election -- voting against his supreme court nominee, Brett Kavanaugh. This isn't a political decision. If this were a political decision for me, I certainly would be deciding this the other way. But, you know, there's an old saying, "History will judge you, but most importantly, you will judge yourself." And that's really what I'm saying. I can't get up in the morning and look at the life experience that I've had, and say yes to judge Kavanaugh. Reporter: It's a decision she knows could cost her her job. If it all comes down to that decision for some voters, was it worth it? Yup. Reporter: No regrets? No. I have no regrets. Reporter: Her Republican opponent, Kevin Cramer, is banking on a Kavanaugh bounce. We are fortunate that Brett Kavanaugh was confirmed even without one of our senators voting for him. Reporter: But Heitkamp says this race comes down to the issues that most impact the rural voters here, like health care and the economy. But now, in the fight of her political life, she told me this. Millions of people in this country live without being a United States senator. It's not the end all and be all. I hope I'm given a chance to serve my country again. But if that service means that you compromise your principles or your values or what you believe is right, you know, it's time for somebody else in north Dakota. Mary, for Heitkamp to have any shot at winning, many say she'll need to have the support of native American voters. But they may not be able to vote because of a new law that requires a street address? Reporter: This fight has been playing out in the courts. And a federal judge says any 11th hour change will create as much confusion as it alleviates. And president trump taking
This transcript has been automatically generated and may not be 100% accurate.