Democrats See a Cash Surge, With a $1.5 Billion ActBlue Haul

In Georgia, the Democrat Jon Ossoff raised $21.3 million, almost four times the $5.6 million brought in by his Republican opponent, Senator David Perdue. Mr. Ossoff’s campaign entered this month with $8.3 million in the bank, roughly the same amount that Mr. Perdue declared.

In his bid to represent Montana in the Senate, Gov. Steve Bullock, a Democrat, drew $26.9 million in the quarter, his campaign announced Thursday, and had nearly $2 million in cash on hand. His Republican opponent, Senator Steve Daines, raised $11.5 million over the same period and reported nearly $3.5 million on hand.

In North Carolina, the Democratic challenger Cal Cunningham — a former state senator who has maintained a narrow lead in his bid to oust Senator Thom Tillis, even as that race has been upended by a texting scandal and health worries in recent weeks — reported raising more than $28 million. Mr. Cunningham’s campaign indicated $4.2 million in cash on hand. Mr. Tillis, seen as one of his party’s more vulnerable incumbents, reported raising $6.6 million and having roughly that same amount on hand to spend.

In Kansas, the Democrat Barbara Bollier reported raising about $13.5 million, a quarterly record for any candidate ever running for any office in Kansas, and ending the quarter with $7.6 million in cash. Her Republican opponent, Representative Roger Marshall, reported raising just over $2.9 million and ending the quarter with $1.7 million on hand.

In Alabama, the Democrats’ vulnerable incumbent, Senator Doug Jones, raised $10.4 million, compared with the $3.4 million reported by his Republican challenger, Tommy Tuberville. Mr. Jones’s campaign reported $7.9 million in cash on hand, compared with Mr. Tuberville’s $1.7 million.

And in Texas, M.J. Hegar, a Democratic former Air Force helicopter pilot challenging Senator John Cornyn, a Republican, reported raising nearly $14 million and concluding the quarter with $8.5 million in cash. Mr. Cornyn, whose place on the Judiciary Committee has also been prominent this month during Judge Amy Coney Barrett’s Supreme Court nomination hearings, reported raising just over half of what his opponent had — $7.2 million — with $8 million in cash on hand.

On ActBlue, the average contribution amount was $47, according to a news release, indicating strong energy among smaller-dollar, grass-roots donors. In a particular sign of strength for the Democrats, the site processed record donations during the weekend after Justice Ruth Bader Ginsburg died.