When Republican Mike Garcia won a Southern California special election in May — reclaiming a district Democrats had flipped only 18 months prior — he gave the House GOP its most encouraging piece of political news since President Trump was sworn into office.

The good news might end there.

While Trump, Minority Leader Kevin McCarthy (R-Calif.) and other GOP leaders have heralded Garcia’s May 12 win as proof that they can win the House majority this year, many other indicators suggest that it will be exceedingly difficult to unwind Democrats’ 17-seat majority come November.

Vulnerable Democratic incumbents have massively outraised their Republican challengers, national GOP groups have yet to show the ability to make up the fundraising gap, and in several key districts, some of the party’s most coveted recruits have opted not to run. Public opinion polls, meanwhile, indicate a Democratic advantage on the congressional ballot in line with what the party enjoyed in 2018, ahead of their sweeping national gains.

Multiple nonpartisan forecasters, in fact, have worsened their outlook for House Republicans in recent weeks, arguing that those structural disadvantages, plus national political head winds for Republicans, will limit GOP House gains — and potentially allow for further Democratic pickups.

“Republicans sincerely believe that 2018 was a high-water mark for Democrats, that it is just not possible that Democrats can improve on their 2018 performance, and I don’t know that that’s true,” said Nathan L. Gonzales, editor and publisher of Inside Elections, who recently declared the California result an “outlier” and predicted that the November election would leave the House “close to the status quo” with no more than five seats changing hands between parties.

GOP leaders see the math differently. Garcia’s win, they argue, shows that Republicans can be competitive in the suburban battlegrounds where Democrats built their majority two years ago — on top of the 30 Democratic-held districts where Trump won in 2016.

“If we can win in the Los Angeles suburbs, we can win anywhere and everywhere we need to win in the fall,” said Rep. Tom Emmer (R-Minn.), chairman of the National Republican Congressional Committee (NRCC), citing 43 Democratic seats with a heavier GOP tilt than Garcia’s.

Democrats and nonpartisan analysts are quick to quibble with that arithmetic — starting with the size of the mountain Republicans have to climb. While the gap is now 17 seats, the margin is certain to be wider. A court-ordered mid-cycle redistricting in North Carolina created two additional safe Democratic seats in that state, and the retirement of GOP Rep. Will Hurd has opened a prime Democratic pickup opportunity in South Texas.

Meanwhile, Democrats are eyeing potential gains elsewhere, including suburban districts outside Dallas and Houston where GOP incumbents are retiring, as well as near-misses from 2018 in central Illinois, southern Minnesota and suburban Atlanta.

That means Republicans may have to flip three or more Democratic seats before they even begin to cut into the current majority, and they face serious head winds in doing so. The most easily quantifiable obstacle is money: More than two dozen Democrats have raised more than $2.5 million each, easily lapping their Republican challengers in all but a few cases.

Data compiled by the Cook Political Report’s David Wasserman found that, as of March, in the 55 top races targeted by the NRCC, the median Democratic incumbent had raised more than six times what the median leading Republican challenger had raised. And that was before the coronavirus pandemic upended political fundraising, making it more difficult for those behind to catch up. Wasserman declared the GOP’s path to the majority as “slim to non-existent” earlier this month.

Outside Republican groups such as the NRCC and the Congressional Leadership Fund are likely to raise tens of millions of dollars to supplement individual campaigns, but those groups have also been trailing their counterparts at the Democratic Congressional Campaign Committee (DCCC) and the House Majority PAC.

Republicans have heavily touted star recruits in several districts — starting with Garcia, a former Navy fighter pilot, son of immigrants and first-time political candidate who skillfully positioned himself as a fresh alternative to his Democratic opponent, state lawmaker Christy Smith. Wesley Hunt, an African American former Army officer, is challenging freshman Rep. Lizzie Fletcher in Texas, and Michelle Steel, a Korean American county official, is running against Rep. Harley Rouda in Orange County, Calif.

“A record number of women running, a record number of minority candidates, 240-some military veterans — these are people with great résumés, and the vast majority of them don’t have voting records,” Emmer said. “It’s basically the Democrats’ 2018 playbook that we’re using.”

But some of those diversity gains have been offset by setbacks elsewhere. Democrats were delighted when GOP voters nominated Jim Oberweis, a conservative former state senator, over two women to face Rep. Lauren Underwood in an exurban Chicago district Trump won by four points. And just this month, party officials moved to distance themselves from Ted Howze, the Republican facing Rep. Josh Harder in a competitive central California district, after Politico reported on racially offensive Internet postings made under Howze’s name.

And on Tuesday, forecasters are closely watching the outcome of the GOP primary in Iowa’s 4th District, where Rep. Steve King is facing a strong intraparty challenge after making racially offensive comments, prompting Republicans to strip him of his committee assignments. A King win, forecasters agree, would leave the seat vulnerable to Democrat J.D. Scholten, who came within three points of beating King in 2018.

Meanwhile, Republicans are likely to go into November with less-than-ideal candidates in several other races. In New York’s 19th Congressional District, which Trump won by seven points in 2016, no credible GOP candidate has emerged to challenge freshman Rep. Antonio Delgado (D). In Michigan, top potential Republican candidates failed to challenge Reps. Elissa Slotkin, who has raised $3.7 million to defend a district Trump previously won by seven points, and Haley Stevens, who has raised $2.5 million in a district Trump won by four.

The difficulties for Republicans have been on display in Utah’s 4th Congressional District, centered on Salt Lake City, where Trump won by seven points in 2016. It leaped to the top of GOP target lists after Democrat Ben McAdams beat GOP Rep. Mia Love in 2018. The NRCC initially backed popular state Sen. Dan Hemmert, who quickly raised more than $400,000. But Hemmert backed out weeks later, citing the demands of a high-profile campaign.

“It’s not the right time. I don’t know what to say,” he told the Salt Lake Tribune in December.

McAdams, meanwhile, has raised $2.8 million for his reelection campaign and had $2.2 million left to spend as of early April. The best-funded Republican candidate, state Rep. Kim Coleman, had about $115,000 in the bank at the same point.

Meanwhile, it’s unclear if potential GOP attacks against McAdams — highlighting his vote for Trump’s impeachment or tying him to far-left Democratic figures — will even resonate in a post-pandemic political environment. McAdams, who recently emerged from a bout with the coronavirus, said Thursday he was focused on helping his constituents and not getting caught up in partisan politicking.

“One thing I have going for me is that I work harder than anybody else in the race, and I think a lot of people who were looking at the race knew that it was going to be hard to outwork me,” he said Thursday.

While there is anecdotal evidence that presidential-year turnout will improve for Republicans with Trump on the ticket, there is little sign that public opinion about control of Congress has shifted since 2018. Democrats won the national House vote in 2018 by about eight points; a Monmouth poll released this month gave them a 10-point lead nationally, and other recent “generic ballot” polls have been in a similar range.

Hopes of outsize GOP gains largely rest on Trump’s ability to keep the pandemic at bay and recover his political standing in the coming months, giving him the ability to drag underfunded candidates across the finish line on Nov. 3.

“President Trump won most of the seats that are on the battlefield now — all he has to do is win them again,” said Rep. Steve Stivers (R-Ohio), a former NRCC chairman. “And so I don’t know if he’ll match his performance from 2016, but if he does, we win the majority.”

But Rep. Cheri Bustos (D-Ill.), chairwoman of the DCCC, expressed complete confidence in an interview Wednesday, calling Garcia’s win “not a sign of anything” and predicting that Smith would best Garcia in the higher-turnout November election.

Bustos pointed to her party’s fundraising advantage, GOP recruiting woes and a proven Democratic message on health care — “I’d much rather be the party of health care than the party of drinking bleach,” she said, referring to Trump’s recent musings about injecting disinfectant — as underpinning that confidence.

“It’s literally failure and failure after failure for them, whether it’s the money, the messaging or the mobilization,” Bustos said. “By every measurement, I feel really good six months out.”