Rich people are spending more than ever to run for Congress. A big test is coming in Maryland.

Wealthy office-seekers plowed more of their own money than ever into runs for Congress last year. Now, the biggest one of all is facing an important hurdle.

Democratic Rep. David Trone has given more than $57 million of his own money to his campaign for Senate in Maryland ahead of next week’s primary — a staggering sum that already ranks among the biggest self-funding campaigns in U.S. history. But he’s not alone: Self-funding congressional candidates gave more to their campaigns in 2023, $131 million, than in any other odd year going back to at least 2003, according to an NBC News review of campaign finance records.

Led by nearly $37 million from Trone last year alone, it’s part of a recent explosion of spending by wealthy candidates that has fundamentally shifted the way campaigns are won and lost — and perhaps made it harder than ever for the non-rich to make it to Washington, since candidates are not bound by donation limits and can give unlimited sums to their own campaigns.

The trend is affecting everything from open-seat primaries for deep red or blue districts across the country to the battle for the Senate. Trone continues to spend heavily as he looks to win the Democratic primary for retiring Sen. Ben Cardin’s seat, before what’s expected to be a costly November battle against former Republican Gov. Larry Hogan. Also running hard for the Democratic nomination is Angela Alsobrooks, the Prince George’s County executive who has won support from some of Maryland’s most prominent Democrats — but has been outspent 9-to-1 by Trone.

Maryland Senate Candidate Angela Alsobrooks (Bill Clark / CQ-Roll Call, Inc via Getty Images file)

“I don’t believe this is the way democracy works. I believe we should have reform in these campaigns,” Alsobrooks said during an April debate sponsored by Fox affiliate WBFF of Baltimore, criticizing Trone’s self-funding and saying her own fundraising was proof of her “broad and growing coalition.” She added: “Money cannot buy you love and it really cannot buy you Maryland.”

Trone has pushed back by arguing that relying on his wealth means he’s not beholden to big donors. During the debate, he listed off corporate PACs that have given money to Alsobrooks in the past and questioned whether those companies have America’s best interests in mind.

“We’ve got to get the money out of the politics that’s really poisoning our system. I’m the only candidate on this stage who doesn’t take money from Exxon. They’re not helping us in the environment, I don’t think,” he said.

Onotse Omoyeni, a Trone spokesperson, echoed Trone’s debate comments in a statement to NBC News, saying the congressman has “refused money from the special interests that pay career politicians to stand in the way of progress.”

“In the Senate, he won’t just refuse that money: he’s already introduced big reforms to our election system, including banning all dark money and special interest money from elections,” Omoyeni added.

Trone leads a big self-funding pack

Trone’s eye-popping spending is part of a long-term pattern for the mega-wealthy co-owner of Total Wine & More. He loaned his own campaigns about $46 million between 2015 and 2022, before he announced his Senate bid. That includes $13 million on his first run for Congress, when he lost a primary for a deep-blue open seat bordering Washington, D.C. He spent yet more to capture his current district in 2018.

But Trone’s self-funding is only the biggest example of a broader trend in congressional races. Candidates gave $61 million to their House campaigns in 2023 and $70 million in the Senate, with nearly half of that coming from Trone in his Senate bid.

Ohio Republican Matt Dolan ($7 million) and Republican Sen. Rick Scott of Florida ($3.5 million) were the next-biggest Senate self-funders in 2023, followed by Ohio Republican Bernie Moreno ($3 million), who defeated Dolan in the Senate GOP primary earlier this year.

Seven other Senate candidates whose campaigns are still active all cut themselves seven-figure checks last year: six Republicans (Maryland’s Robin Ficker, Utah’s Brad Wilson, Florida’s Keith Gross, Montana’s Tim Sheehy, Michigan’s Sandy Pensler and Pennsylvania’s Dave McCormick) and one Democrat, Florida’s Stanley Campbell.

Seventeen House candidates gave their campaigns at least $1 million last year; former Rep. Gil Cisneros, D-Calif., loaned his campaign $2.4 million to finance his attempted return to Congress, and Rep. Shri Thanedar, D-Mich., gave his campaign more than $2 million.

There’s been a fairly steady increase in congressional campaign self-funding in recent years, and a massive leap since the early 2000s.

Congressional candidates loaned their campaigns about $14.6 million in 2003. The amount of off-year self-funding increased to almost $22 million in 2005 and $36 million before ballooning to more than $62 million in 2009, after the election of President Barack Obama and at the beginning of the tea party Republican wave.

Self-funding ticked down in the subsequent years. But the Donald Trump years kick-started the self-funding again after the famous businessman took the White House. Wealthy candidates poured almost $93 million into House and Senate campaigns in 2017 and $64 million in 2019, before a massive increase to almost $126 million in 2021 — followed by the $131 million in 2023.

Similarly, the number of candidates willing to seed their campaigns with early money has gone up, too: The 11 Senate candidates to give themselves at least $1 million in the off year is more than all other years except 2021, when 13 candidates did it, and the 17 House candidates to do so is more than ever.

These early infusions of personal wealth don’t necessarily decide who wins campaigns. Just 11 of the 90 congressional candidates who gave their campaigns at least $1 million in the off year since 2003 have gone on to win House and Senate races.

That’s about 12%, a relatively low winning percentage overall — but a figure that looks far more impressive considering there are thousands of congressional campaigns each year, and most of them lose, too. And that figure doesn’t take into account candidates who loan their campaign seven-figure sums the same year as their election, like Trone did during his multiple bids for the House.

Leaning on personal wealth early in the process can be an important accelerant for a campaign, giving it the ability to ramp up things like staff, messaging and advertising quickly without having to wait to build out a fundraising infrastructure.

That’s one reason why self-funding is particularly attractive for nonincumbent candidates: A recent OpenSecrets analysis found that 88% of self-funding in 2023 went to candidates running in open seats or challengers, instead of incumbents. That share includes Trone, as he’s running for an open Senate seat. But even when he’s not included, a significant majority of self-funding is still by candidates in open seats or challengers running against incumbents.

This article was originally published on NBCNews.com