Washington (CNN) North Dakota Sen. Heidi Heitkamp announced Thursday she will vote against Brett Kavanaugh's Supreme Court confirmation and, in doing so, risked enraging voters in her deep-red state just a month before they decide whether to keep their only Democratic statewide officeholder.

Heitkamp already trailed by double-digits in two recent public polls. And Republicans believe opposing Kavanaugh will help her GOP challenger, Rep. Kevin Cramer, rally conservatives who might have been willing to break ranks or sit November's midterms out. President Donald Trump won North Dakota by 36 percentage points in 2016.

Heitkamp admitted the political risk in a Thursday interview.

"This isn't a political decision. If this were a political decision for me, I certainly would be deciding this the other way," she told WDAY in North Dakota.

"You know, there's an old saying: History will judge you, but most importantly, you'll judge yourself. And that's really what I'm saying," she said. "I can't get up in the morning and look at the life experience that I've had and say yes to Judge Kavanaugh."

There's also the possibility that Heitkamp -- who appears to be the Senate's most endangered Democrat -- sees polls that show her trailing and has concluded that she has nothing to lose.

The North Dakota Republican Party quickly attacked the vulnerable senator for opposing the nomination, arguing that the decision aligns her with the liberal wing of the Democratic Party.

"Heidi Heitkamp just sided with liberals Chuck Schumer and Nancy Pelosi to obstruct President Trump and oppose the exceptionally qualified Judge Brett Kavanaugh," Jake Wilkins, a spokesman for the North Dakota GOP said in a statement.

But there are possible political upsides for Heitkamp in opposing Kavanaugh, too.

Among them: She could energize her base, which is small in North Dakota but without which she'd stand no chance against Cramer, and avoid turning off independent women, who she needs to win overwhelmingly. She might also turbocharge her fundraising from online, small-dollar progressive donors.

And by not breaking ranks with her fellow Democrats, she'll preserve a future in Democratic politics should she lose in November, allowing her to remain a player within a party that is stridently opposed to confirming Kavanaugh and handing conservatives a 5-4 majority on the Supreme Court.

Heitkamp was at times critical of Kavanaugh during the confirmation process, which means she'll also avoid charges of voting for him out of political expediency.

Heitkamp was one of three Senate Democrats to break with the party and vote to confirm Neil Gorsuch, Trump's first Supreme Court nominee, last year.

But the stakes were much lower in that fight, in which Republicans were replacing a staunch conservative on the court in Antonin Scalia, rather than a swing vote, Anthony Kennedy.

"Her vote for Gorsuch allows her to frame this as 'I would have voted for a Trump (nominee) but not one credibly accused of sexual assault,'" tweeted Democratic strategist Kait Sweeney, a veteran of Bernie Sanders' presidential campaign. "Works on (independents) moving away from GOP over Kavanaugh."

Some Republicans were quick to criticize Heitkamp's move as a calculation for life after the Senate.

"Heitkamp knows what everybody else does: She's soon to be a former Senator so she might as well impress a future Democratic employer," tweeted Josh Holmes, the top political adviser to Senate Majority Leader Mitch McConnell, R-Kentucky.

In a statement, Heitkamp said Kavanaugh's behavior in last week's Senate Judiciary Committee hearing, in which California professor Christine Blasey Ford, who accused Kavanaugh of sexually assaulting her when they were both in high school, led her to question his "current temperament, honesty, and impartiality."