She is the most vulnerable Senate Democrat running for reelection in November, if not the most vulnerable senator on the ballot in 2018. Her race, in a state President Trump won by 36 points, is ground zero for the argument that the drama surrounding Brett M. Kavanaugh’s nomination to the Supreme Court may actually help Republicans keep control of the Senate.

Yet, Sen. Heidi Heitkamp (D-N.D.) is voting against Kavanaugh for the Supreme Court, a decision that thins the margin of error Republicans have to confirm Kavanaugh. That’s despite one local poll taken after Kavanaugh was accused of sexual assault showing 60 percent of North Dakota voters want Kavanaugh confirmed.

So did Heitkamp just vote against her own political interests, or is there some other political calculation here? Here is a look at why Heitkamp decided to buck the conventional wisdom and vote against Trump’s Supreme Court justice.

Kavanaugh’s partisanship in his defense of himself from sexual misconduct allegations was too much: If you parse her official statement, the fact that Kavanaugh came out swinging against Democrats is the No. 1 reason Heitkamp is voting against him. He’s just not fit to be on the Supreme Court after that, she seems to be saying. " … [L]ast Thursday’s hearing called into question Judge Kavanaugh’s current temperament, honesty and impartiality,” she says. “These are critical traits for any nominee to serve on the highest court in our country.”

She draws a direct comparison with Supreme Court Justice Neil M. Gorsuch, whom she did vote for last year and who she thought was not nearly as ideological. North Dakota is a state where bombast like the kind Kavanaugh displayed just rubs people the wrong way, Democratic operatives there say.

She sees an opening to make her Republican opponent look bad: Heitkamp said she heard from “countless” women across the state who shared stories mirroring the one Christine Blasey Ford testified about involving Kavanaugh. Her office said outreach from North Dakotans came to 52 percent of constituents supporting Kavanaugh and 46 percent opposing him.

She also mentioned that she was the state’s attorney general, where she pushed for legislation protecting women from domestic abuse and violence.

Contrast that with her challenger, GOP Rep. Kevin Cramer, who recently asked whether, even if Kavanaugh did try to rape Ford as he allegedly stifled her screams when they were in high school, it should disqualify him from the Supreme Court. Cramer also nearly immediately said he’d support Kavanaugh after Ford accused him, whereas Heitkamp said she was waiting for the FBI investigation to make her decision.

Cramer has been leading in most polls, and he really started to surge right around the time an NPR/PBS News Hour/Marist poll showed national Republican enthusiasm to vote catching up to Democrats. Conventional wisdom was that Heitkamp had no choice but to vote for Kavanaugh against that backdrop.

But by voting against Kavanaugh, did Heitkamp find a way to contrast herself with Cramer among independent female voters on an issue that everyone is paying attention to? It’s risky. But now, at least she can run ads attacking Cramer for what he said.

Her campaign feels more comfortable than national polls suggest: Democratic operatives in North Dakota and Washington have warned all year against assuming Heitkamp will lose because her state went so heavily for Trump in 2016.

If she can keep the Democratic base motivated (something Democratic insiders say the Kavanaugh nomination has helped with) and if she holds on to some Trump voters who personally like her, Heitkamp could win, they theorize.

Heitkamp’s campaign says polls they have show her performing well in all the key areas of the state she needs to win.

She believes Ford: Shortly after the #MeToo movement got started last year, Heitkamp was one of four female senators who agreed to go on NBC’s “Meet The Press” and talk about sexual harassment in and around their lives. It’s clearly an issue close to her, and she underscored that in an interview Thursday with WDAY in North Dakota:

“This isn’t a political decision. If this were a political decision for me, I certainly would be deciding this the other way. But there’s an old saying, history will judge you, but most importantly you’ll 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."