(CNN) - Democratic challengers in the eight most competitive Senate contests collectively raised a staggering $261.8 million during the third quarter, lapping the $96 million collected by all the Republican incumbents they are trying to oust, new filings show.
The wide chasm in fundraising points to Democratic donors' over-the-top enthusiasm about seizing the chamber and is certain to deepen the worries of GOP candidates, already fretting that President Donald Trump's unpopularity will serve as a drag on down-ballot Republicans.
"It's very clear from what we are seeing in polling and fundraising numbers that the momentum and enthusiasm is on the Democratic side," said Doug Heye, a Republican strategist and CNN contributor. "When an incumbent (president) is unpopular, he takes people with him, and that's the concern now."
In contest after contest, Democratic Senate candidates posted eye-popping sums -- from the record-shattering $57.9 million raised by Jaime Harrison in South Carolina to the $39.4 million collected by Sara Gideon in her challenge to Maine Republican Sen. Susan Collins.
In Iowa, Democratic challenger Theresa Greenfield raised more than $28 million to Republican Sen. Joni Ernst's nearly $7.2 million.
But many candidates also burned through their cash quickly in recent months.
In North Carolina, a race that has seen more advertising than almost any other Senate contest this year, Democrat Cal Cunningham took in $28.3 million in the July-to-September period -- more than four times the haul of Sen. Thom Tillis, the Republican he's trying to replace.
But a spending spree that topped $30 million over the last three months left Cunningham with smaller cash reserves than Tillis in a race unsettled by 11th hour revelations that Cunningham sent romantic text messages to a woman who is not his wife.
In neighboring South Carolina, Harrison also spent more than he raised, disbursing $60.1 million during the three-month period, according to new filings with the Federal Election Commission. His campaign plowed most of the money into advertising, ranging from billboards and television commercials to print ads in HBCU Times, aimed at students and alumni of historically black colleges.
The heavy spending left Harrison with just shy of $8 million in cash reserves. Republican Sen. Lindsey Graham, the three-term senator Harrison is trying to oust, raised far less than Harrison but started October and the final sprint to Election Day with roughly $14.8 million remaining in his campaign war chest.
In half of the eight races examined, four of Democratic challengers and six Republicans incumbents spent more than they raised in the quarter.
In other states, they came close. In Iowa, for instance, Greenfield spent nearly $25 million in three months, or more than 86% of what she took in. Ernst spent nearly $12 million. And advertising by outside groups and political parties has helped make the Senate race in the Hawkeye State one of the most expensive in the country at more than $178 million, according to Kantar/CMAG's tally.
These days the advertising is so heavy in Iowa, "you have to feel bad for every car dealer in the state," said Jeff Link, a Des Moines-based Democratic strategist. "It's just back-to-back political ads."
But the filings this week with the Federal Election Commission also underscore a key advantage for Democrats in the weeks ahead: The support for their campaigns among small-dollar contributors.
In six of the eight key contests, the Democratic challenger raised more of their funds from small-dollar donations than their Republican opponent did.
ActBlue, the online platform for Democratic candidates and causes, announced this week that is processed a whopping $1.5 billion online during the third quarter, swamping the $623.5 million taken in by WinRed, the online platform Republicans launched last year to serve as a counterweight to ActBlue.
Democrats' continued ability to harness low-dollar contributions already is forcing Republicans once again to reexamine their fundraising infrastructure. Donors who give in small amounts can be tapped repeatedly for additional contributions before they hit the $2,800 limit on what they can donate in a general election to a single candidate.
"We are getting buried in an avalanche of blue money," Dan Eberhart, an energy executive and Republican donor, said in an email Friday morning.
"The Democrats are able to raise millions overnight in $5 and $10 increments," he said. "We are going to need to rebuild our digital fundraising capabilities."
Red states, blue dollars
In deep-red Alabama, the Senate's most vulnerable incumbent Democratic Sen. Doug Jones also saw a fundraising surge: He collected $10.4 million between July 1 and September 30, up from nearly $2.7 million during the previous quarter.
His Republican challenger, former Auburn head football coach Tommy Tuberville, raised a little less than $3.4 million during the third quarter.
Even in contests viewed as longshots for Democrats, the liberal money spigot remains wide open.
In Kentucky, Democrat Amy McGrath raised nearly $36.9 million in the quarter, more than twice the $15.8 million collected by the powerful Republican she wants to unseat, Senate Majority Leader Mitch McConnell.
McGrath started October with nearly $20 million in cash reserves to McConnell's $14 million,
In Alaska, independent Al Gross, who is the Democrat nominee, outraised Republican Sen. Dan Sullivan by about 8-to-1 and started the final to push to Election Day with twice as much available cash.