After sitting out the GOP primary to date, some House Republicans from districts President Biden carried in 2020 plan to start throwing their support behind former President Trump, Axios has learned.

Why it matters: Trump is reasserting his dominance over the GOP as he zeroes in on the nomination — even with Republicans who are gambling their political fortunes by embracing his brand.

Driving the news: Rep. Nick LaLota (R-N.Y.) on Saturday became the first of the 17 Biden-district House Republicans to throw his support behind Trump.

• "President Trump's policies made our nation stronger and had us on track to prosperity," the Long Islander said in a statement. "I endorse President Trump to be our 47th president and look forward to him cleaning up the mess President Biden created."
• LaLota represents one of the reddest Biden districts — and it could be made even more Republican in redistricting.

What we're hearing: LaLota likely won't be alone for long.

• "I expect to ultimately endorse Donald Trump for president," Rep. John Duarte (R-Calif.), whose district voted for Biden by nearly 11 percentage points in 2020, told Axios.
• Duarte said the GOP primary is "consolidating fast" and that he "will strongly support the Republican candidate," adding, "We need to save America from Joe Biden's frailties, corruption and failures."
• Another Biden-district Republican who spoke on the condition of anonymity told Axios they plan to endorse Trump, though their timeline is uncertain.

State of play: Trump is facing off with former South Carolina Gov. Nikki Haley on Tuesday in the New Hampshire primary, with polls suggesting the former president is on track to win decisively.

• The RealClearPolitics polling average has Haley trailing Trump by 18.2 percentage points in New Hampshire — and facing even larger deficits in South Carolina and nationwide.
• Trump's landslide win in the Iowa caucuses and Florida Gov. Ron DeSantis' exit from the race have prompted a sudden burst of new endorsements for Trump, most recently from Rep. Nancy Mace (R-S.C.).

Zoom in: One key Trump endorser is House Republicans' campaign chief.

• "Iowa sent a strong signal that Republican voters want the party to unify behind Donald Trump," National Republican Congressional Committee Chair Richard Hudson (R-N.C.) said in a post on X on Sunday.
• "He is the presumptive nominee. It is time to come together, kick Joe Biden out of office, and get our country back on track," Hudson added.

Between the lines: GOP strategist Mike Madrid, in an interview with Axios, predicted the "vast majority" of Biden-district and swing-district Republicans will end up supporting Trump.

• "The calculation is: Can you risk alienating ... your base by not supporting him and then taking your chances with the moderates?" he said, noting college-educated swing voters in places like New York and California are an increasingly tough sell for even down-ballot Republicans.
• The GOP base is "moving from college-educated to non-college-educated voters," Madrid said — making Republicans more reliant on the low-propensity voters Trump turns out in presidential elections.

The other side: "It's no surprise the so-called moderate Republicans are 'bending the knee' to Trump and lining up to endorse him," Democratic Congressional Campaign Committee spokesperson Courtney Rice told Axios.

• "The DCCC is committed to making sure their decision to put fealty to the MAGA agenda over their constituents will cost them their seats in November."