Bernie Sanders reported Tuesday that he raised $25.3 million over the last three months, the largest quarterly sum a Democratic White House hopeful has posted this year and an amount that ensures he will be an enduring presence in the primary.

Pete Buttigieg, who entered the race as the little-known mayor of South Bend, Indiana, also released his numbers, pulling in $19.1 million for the quarter, an almost $6 million dip from his field-leading sum last quarter but a figure that’s all but certain to place him in the top tier.

The large sums, which were posted after the notoriously dry summer fundraising months, come as both candidates have faced skepticism about their prospects. Buttigieg has struggled to break out of single-digit polling, while Sanders has faced a drumbeat of speculation that progressive rival Elizabeth Warren is eating into his support.

Taken together, they offer a clear sign that both candidates will have ample resources to compete well into the primary, with Sanders announcing his first TV ad buy of the campaign on Tuesday.

“Media elites and professional pundits have tried repeatedly to dismiss this campaign, and yet working-class Americans keep saying loudly and clearly that they want a political revolution,” Sanders campaign manager Faiz Shakir said in a statement.

Sanders has repeatedly condemned rivals who rely on big-dollar fundraisers, instead championing his army of online donors who give small amounts. Yet the Vermont senator is holding similar events and earlier transferred $10 million from his other campaign accounts, a portion of which was raised in the kind of ritzy environments he’s blasted.

He now bills these as “grassroots” fundraisers and was set to hold one such event in Las Vegas on Tuesday. In June, $2,000 tickets for a San Francisco fundraiser sold out. A Los Angeles event in July that charged as much as $2,800 featured rapper Vic Mensa.

A Sanders spokeswoman, Sarah Ford, said in an email that the basic cost of entry is $27 and “no one is required to donate any amount above that to attend.”

For candidates, there’s a growing sense of urgency as the primary becomes a fierce battle for a limited pool of cash. In the days and hours before Monday’s deadline, they pleaded for money, making appeals on social media and collectively blasting out more than 80 emails asking supporters to “chip in” $5, $10 or $50. The third-quarter figures have to be reported to the Federal Election Commission by Oct. 15.

Those outside the top tier are facing pressure to post competitive numbers or get out, though their exits couldn’t come soon enough for some angsty Democrats. They will not only face challenges paying for advertising to amplify their message, but are also likely to struggle reaching fundraising thresholds set by the Democratic National Committee to qualify for future debates.

“If you are being outraised 3-to-1 by Elizabeth Warren, Bernie Sanders or Joe Biden, you have no viable path to victory,” said Rufus Gifford, Barack Obama’s former finance director. “Even if you can compete in the early states … shortly thereafter you will run out of money.”

Cory Booker recently warned that unless he juiced his fundraising numbers by an additional $1.7 million he’d likely have to drop out. The New Jersey senator announced Tuesday he was “proud” of his team for surpassing the goal while pulling in a total of $6 million for the quarter.

But campaign manager Addisu Demissie then issued a memo stating they’d have to do even better and raise $3 million by the end of October.

Montana Gov. Steve Bullock, who has also struggled to raise money, is applying for public financing, turning to a fund that is replenished by those who volunteer to chip in $3 from their taxes. He hopes it will supplement his campaign with a $2 million fundraising boost.

The third quarter came to a close as Trump faces an impeachment inquiry in Congress related to his attempts to get the Ukrainian government to investigate Biden. The development has scrambled politics in Washington but has turned into a fundraising rallying cry for both major political parties.

Trump has turned his outrage over the inquiry into a flood of campaign cash. Trump and the Republican National Committee reported raising $13 million in the three days after House Speaker Nancy Pelosi announced the probe last week. And Trump’s son Eric tweeted later that the total grew to $15 million.

That’s on top of what’s already expected to be a major haul for the quarter. Trump and the RNC previously reported pulling in more than $210 million since the start of 2019, more than all his Democratic rivals combined.

That’s a source of worry for some Democrats, who fear it will be hard to catch Trump once a nominee is selected.

“Trump’s presidency is wounded but not mortally wounded, and their operation is as good as it gets,” Gifford said.

Like Trump, some Democrats have treated the impeachment inquiry as a fundraising opportunity. Biden ramped up Facebook ad spending that seized on unfounded allegations made against him and his son Hunter by Trump and his allies.

Sanders, Warren and California Sen. Kamala Harris have done similar.

One recent Biden ad said Trump was “trying to distract you from what’s really at stake for your family by spreading lies about my family,” and his campaign says they’ve seen a significant uptick in donations.