CONWAY, Ark. — To many Democratic leaders, the path to power in Washington looks like Clarke Tucker.

He supports the Affordable Care Act, but not a single-payer system. He signals misgivings about Nancy Pelosi as the next House speaker. And even when addressing an audience of Democratic Party regulars, he does not attack President Trump by name.

In short, he comes across as a moderate — and exactly the kind of candidate who leading Democrats believe the party should field in Republican-leaning districts to bolster the majority they hope to win in the House in November.

But that strategy frustrates the party’s liberal supporters, who feel the wind at the Democrats’ back and worry about using it to crowd their House caucus with members who may feel inclined to buck the party leadership and stray from its policy agenda.

Though much of the Democratic energy nationally is coming from the party’s left, Tucker appears to be running well ahead of a clutch of more liberal rivals in the May 22 primary for a seat in central Arkansas.

“There’s, in my view, an overly simplistic characterization of Democrats now into one of two camps: either centrist and unenthusiastic or liberal and passionate,’’ Tucker, a state legislator, said in an interview after he spoke at a Faulkner County Democratic Women lunch on May 7.

“I have a lot of passion about the issues that I really care about,’’ he said. “At the same time, I realize that making any progress is better than making no progress at all.’’

His broad, incremental approach can feel unsatisfying to more confrontational Democrats. Even more aggravating for them is the support Tucker has received from the Democratic Congressional Campaign Committee in Washington, which anointed him as its preferred candidate to challenge the district’s Republican incumbent, French Hill.

“Is it really worth the win to keep pushing back against the people you’re supposed to be serving?’’ said Paul Spencer, one of Tucker’s primary opponents. “The party used to stand for something. At some point, you’ve got to stand up, and you’ve got to move the party in the right direction.’’

In a string of important races across the country, national Democrats have been embracing recruits near the political center, hoping they will give the party the chance to compete in states like Utah and Kansas where a liberal Democrat might stand little chance of winning.

About a dozen crucial House races this fall are likely to feature Democratic nominees who are positioned markedly closer to the middle than the national party’s activist base — more than enough to determine control of the House.

The party scored an early upset with such a candidate, Conor Lamb, in a Pennsylvania special election in March. Lamb, a veteran, opposed Pelosi, single-payer health care and most new gun regulations, but with a populist economic message captured a district Trump carried easily in 2016.

Democratic voters have largely been going along in the primaries held so far in these districts, which are often in rural areas. In Illinois the voters chose Brendan Kelly, a prosecutor with a mend-it, don’t-end-it message on the Affordable Care Act, to take on a conservative Republican in a rural district.

And on Tuesday, Democrats in several states that Trump carried in 2016 selected ideological mavericks to carry their banner in difficult House races.

One was in Indiana, where Mel Hall, a businessman and former minister who has made political donations to Republicans, dispatched rivals on the left who called him an unreliable Democrat.

Another was in West Virginia, where Richard Ojeda, a fiery populist running for an open seat in the southern part of the state, has boasted of having voted for Trump in 2016.

Representative Josh Gottheimer of New Jersey, a first-term Democrat who wrested his closely divided district from a hard-line Republican in 2016, said his party should strongly back moderate candidates who have the potential to compete in areas that often prove politically grim for Democrats.

Gottheimer urged liberal Democrats to accept some ideological dissension in the party’s ranks to achieve a congressional majority.

“If we’re going to win some of the places we can win, in redder parts of the country, it’s with people who may not be aligned on certain issues with some other Democrats,’’ Gottheimer said.

The House Democrats’ campaign committee has not hesitated to back relatively moderate candidates, even in less red areas, when the group concludes that a less strident nominee would give the party its best chance of winning.

In central Arkansas, its seal of approval went to Tucker.

His district, the 2nd, stretching from the small towns of Saline County through Little Rock and toward the strawberry stands around Bald Knob, has tilted toward Republicans in recent years, but it is not inherently safe territory. A Democrat held the seat as recently as 2010, and Trump won only a bare majority there in 2016.