(CNN) Donors sent a wave of fresh money this month to North Dakota Sen. Heidi Heitkamp, one of the Senate's most endangered Democratic incumbents, in the days after she voted to oppose Brett Kavanaugh's ascension to the Supreme Court.

Heitkamp collected an eye-popping $12.5 million during the first 17 days of October, more than three times the $3.8 million she raised during the entire July-to-September fundraising quarter. Donors who give in small amounts fueled about 60% of her individual contributions.

The cash tsunami underscores how the contentious process surrounding Kavanaugh's confirmation has stirred activists. Republicans say they too have seen a donor outpouring in response to the drama of the Kavanaugh hearing and the razor-thin vote to send him to the nation's high court.

The GOP-controlled Senate confirmed Kavanaugh this month following a high-profile hearing and FBI investigation into allegations of sexual assault lodged against him. Kavanaugh has denied any wrongdoing.

Heitkamp announced her opposition to Kavanaugh in early October. By voting no, she bucked conventional wisdom and risked her re-election prospects in a state that backed President Donald Trump by a wide, 36-point margin in 2016. She faces GOP Rep. Kevin Cramer on November 6.

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