When Democrat Jan McDowell ran for the 24th Congressional District last year, few outside the North Texas district were paying attention. Then something funny happened: She came surprisingly close to winning, losing to U.S. Rep. Kenny Marchant, R-Coppell, by just 3 percentage points.

Now, Marchant's seat is one of six GOP-held congressional districts that national Democrats are targeting in Texas, and McDowell is running again — except this time, so are at least four other Democrats in what is already the state's most crowded U.S. House primary.

"I clearly made it look too easy," McDowell said jokingly in a recent interview. The Democratic newcomers can be frustrating, she added, "but my take has always been that I’m expecting there to be lots of candidates in the primary, and I’m fine with that. I’m working to earn the votes of people who backed me before and didn’t back me before."

The situation in the 24th District is emblematic of a broader trend across the state. As national Democrats zero in on Texas as the linchpin of their 2020 strategy, the primaries are filling up with a mix of candidates who ran last time and new entrants encouraged by the post-2018 political landscape.

In four of the six targeted districts, the Democratic nominees from last time are already running again. In a fifth district, the runner up from the Democratic primary is pursuing a rematch.

The primary fields are still taking shape, but one of the early choices they are presenting to primary voters is crystallizing: Should voters stick with the candidate who helped move the needle last cycle or go with someone new to finish the job?

The candidates who are running again seem cognizant of the dynamic. Mike Siegel is making a second bid for the 10th District after coming within 5 percentage points of U.S. Rep. Michael McCaul, R-Austin, last year. He said it is a "fair question" for primary voters to ask whether he is ready for the higher stakes this time around.

"I hear that potential criticism, and I’m taking action to show that this campaign is going to fulfill the requirements for a campaign that is a national battleground, that will be tightly contested, where you’re going up against a very well-funded incumbent," Siegel said.

Siegel entered the 2020 primary in January, 11 months earlier than when he got in the race last time — and he quit his job days later. He raised more in the first quarter this year than he did during the entire 2018 primary. And he said he is working to professionalize his campaign in ways that he was unable to during the last election cycle, when he could not find a campaign manager.

The newcomers in the 10th District include Austin doctor Pritesh Gandhi and Austin lawyer Shannon Hutcheson. Both quickly proved their seriousness, with Gandhi raising about $161,000 within the first month of his candidacy and Hutcheson raking in over $165,000 after just two days as a candidate.

In Marchant's district, the Democratic field numbered at least half a dozen candidates earlier this year — one has since dropped out. Those remaining include McDowell; Kim Olson, the 2018 nominee for agriculture commissioner; John Biggan, the runner-up to McDowell in the 2018 primary for the seat; and Candace Valenzuela, a Carrollton-Farmers Branch school board member.

In an interview shortly after she began her campaign in April, Valenzuela addressed the new-old dichotomy.

"As a candidate coming up, you should acknowledge and treat with utmost respect the work that they’ve done, and I do," Valenzuela said. "That’s not to say that I’m not the best candidate for the district as it exists right now."

In the 22nd District, Sri Preston Kulkarni is making another bid after losing to U.S. Rep. Pete Olson, R-Sugar Land, by 5 percentage points last year. But before he can face Olson again, Kulkarni has to face fellow Democrat Nyanza Moore, a lawyer and local political commentator who said she voted for Kulkarni in 2018 but decided to get in herself after he came up short.

"When you have a faction of fresh faces, the benefit is that we have not lost before," Moore said. "When you’ve already run, no matter what the reason was that you lost, it was still a defeat. And that defeat left Democrats with the same old same old from Pete Olson."

Kulkarni made a splashy entrance into the 2020 primary in early April. He simultaneously unveiled a star-studded endorsement list that included U.S. Rep. Joaquin Castro of San Antonio, former gubernatorial nominee Wendy Davis and former Houston Mayor Annise Parker.

Kulkarni is not the only comeback candidate looking to create early frontrunner status. Gina Ortiz Jones, who is running for the 23rd District again after narrowly losing last year to U.S. Rep. Will Hurd, R-Helotes, has received a few major endorsements in her campaign's opening month, including from EMILY's List, the influential national group that works to elect Democratic women who support abortion rights. EMILY's List backed Jones in 2018 — but not nearly as early in her candidacy.

There is one targeted primary that bucks the trend — sort of. In the 21st District, where national Democrats are hoping to knock out U.S. Rep. Chip Roy, R-Austin, 2018 Democratic nominee Joseph Kopser made clear early on this cycle that he would not run again. But a 2018 candidate from another congressional district, Jennie Lou Leeder, is running for the 21st District this time, and another not-so-newcomer is considering a campaign: Davis, the 2014 gubernatorial candidate.

Republicans have not been shy about deriding the primary fields as being filled with political has-beens.

"The fact that Texas Democrats are about to nominate a slate of socialist losers already rejected by voters shows how unserious they are about competing in conservative congressional districts in 2020," said Bob Salera, a spokesman for the National Republican Congressional Committee.

Disclosure: Joseph Kopser has been a financial supporter of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.