Democrat Jon Ossoff reported another unprecedented fundraising haul Thursday in the race for Georgia's 6th District, collecting an additional $15 million in roughly the last two months in a race that's already the most expensive of its kind.

So vast it filled about 58,000 pages, Ossoff’s fundraising shattered the quarterly record he set earlier this year, when the former congressional aide astonished the political world by collecting more than $8.3 million.

All told, he’s raised about $23.6 million in a quest to flip the suburban Atlanta district. And he's burned through most of it: He reported about $1 million left in the bank.

It was not immediately clear how much of the donations came from out-of-state, but his last report showed only about 1 in 20 contributions were from Georgia residents. His campaign said the average donation was $20.49.

Republican Karen Handel, his opponent in the June 20 runoff, reported late Thursday that she raised more than $3.8 million during the same two-month period. She had about $1.4 million on hand.

The staggering fundraising report underscores the national attention on the contest, considered a must-win by both parties. Costing more than $40 million overall, the race is by far the most expensive U.S. House election in the nation's history.

An Atlanta Journal-Constitution analysis shows that includes about $25 million spent or reserved for advertising since April 18, when Handel and Ossoff notched spots in the June 20 runoff. Democrats have outspent Republicans by nearly $2 million in the runoff phase.

Handel's campaign said she's faced an unprecedented flood of out-of-state money "raised from Nancy Pelosi and the 'resistance' to fund ads falsely attacking Karen. We are confident that the people of the 6th are not going to let Pelosi's puppet steal a seat in Georgia."

Handel has a history of struggling to raise cash, hobbling her previous campaigns for governor and U.S. Senate. She took in more than $460,000 in her earlier fundraising report - an otherwise respectable take that paled in comparison to Ossoff.

She far exceeded that total this fundraising cycle. She's had fundraisers with President Donald Trump, House Speaker Paul Ryan and other GOP leaders. And she is set to hold another event Friday with Vice President Mike Pence, who is flying into Dobbins Air Reserve Base in the early afternoon.

Her campaign has also been buoyed by a flood of outside spending since her No. 2 finish in the first round of voting. While Handel has reserved about $2.2 million in ad spending through the runoff, GOP groups have reinforced her with more than $9 million in additional spending.

Ossoff is getting backup as well: The Democratic Congressional Campaign Committee has spent $4.3 million in the runoff phase, and other left-leaning groups have chipped in around $500,000. But his fundraising totals means he hasn’t needed as much additional firepower.

Contrast the flood of spending in Georgia with the other recent House special elections. Montana’s air wars cost about $10 million, though Democrats only reluctantly helped Rob Quist after weeks of attack ads from GOP groups. And less than $200,000 was spent by outside groups in the Kansas race.

Both those contests were fought over reliably Republican districts that Donald Trump won by 20 points or more. And in both, national Democrats were squeamish about pumping in more resources into campaigns they saw as doomed.

Georgia’s 6th District, which spans from east Cobb to north DeKalb, has also long been a GOP stronghold. But Trump won the district by less than 2 points, and Democrats were buoyed by Ossoff’s near-miss of an outright victory on April 18.