The words were barely out of Sen. Heidi Heitkamp’s mouth before her opponent was already slamming her decision.

Heitkamp, a Democrat from red state North Dakota, ended the suspense over her choice in the confirmation of Supreme Court nominee Brett Kavanaugh on Thursday when she announced she was voting "no."

Her Republican opponent in her re-election bid, Rep. Kevin Cramer, quickly fired back at Heitkamp’s decision in a tweet accusing her of siding against the people of North Dakota.

“I'm deeply disappointed with Senator Heitkamp's decision to vote no on Judge Kavanaugh's nomination to the Supreme Court,” Cramer said in the tweet. “Clearly, she has decided to vote with Chuck Schumer, and not the people of North Dakota.”

Heitkamp’s decision may put her in line with her fellow Democrats in the Senate, but it also comes at peril. Heitkamp is in a tough re-election battle in a state Trump won by almost 36 percentage points. Trump cast her as a "liberal Democrat" during a rally in Fargo.

"You need a senator who doesn't just talk like they're from North Dakota but votes like they're from North Dakota," Trump said at the June event.

On Kavanaugh, Heitkamp told WDAY, a TV station in Fargo, "the process has been bad, but at the end of the day you have to make a decision and I've made that decision."

"I will be voting no on Judge Kavanaugh," she said.

The Associated Press contributed to this report.