Five weeks after their Election Day thumping, Republicans in the House of Representatives are still arguing internally over President Trump’s role in the 40-seat thrashing of their majority.

House Republicans aligned with Trump, most of whom survived the midterm elections, are blaming November’s steep losses on disloyalty to the president and resistance to his agenda. Republicans from the suburbs, where Democrats experienced major gains, are mocking that argument and pointing to Trump and his laser-like focus on immigration as the chief culprits in their downfall.

Some party insiders working to usher a rebound in 2020 are casting most of the blame on the White House, saying Trump's highlighting of immigration in the final days to gin up the base backfired.

"There's a serious conversation a lot of us are having," Rep. Adam Kinzinger, R-Ill., told the Washington Examiner on Monday, describing the debate as fairly intense. "Some areas we out-performed, but especially if you look at the suburbs, we didn't. For us, to want to be a healthy party going forward, it's important to recognize that."

Republican operatives in the 2018 trenches, now formulating battle plans for the next election, are backing the suburban Republicans blaming Trump for their ejection from Congress. In reviewing polling and other data, they discovered that the president’s provocative immigration rhetoric was more damaging to the House GOP during the final seven to 10 days than they realized at the time.

Trump hammered on the migrant caravan as he barnstormed red states to stump for Republican Senate candidates in the homestretch while also raising the specter of eliminating birthright citizenship for the children of immigrants. The president’s near-singular focus on those issues repelled Hispanics, independents and soft Republicans, turning a race for House control that leaned Democratic into a late-breaking GOP bloodbath.

“The election was much more about Trump than we wanted to admit at time,” a veteran Republican strategist said.

Trump loyalists in Congress tend to agree that November was about the president, as is often the case in midterm elections. But their diagnosis of what felled the GOP majority diverges from the conclusions reached by many suburban Republicans.

"We would have done a much better job of keeping the House of Representatives if we had more forcefully and vigorously supported the Make America Great Again agenda, most specifically relating to border security, repeal of Obamacare and deficit and debts," Rep. Mo Brooks, R-Ala., said.

Outgoing Rep. Mia Love, R-Utah, defeated in a suburban Salt Lake City seat, disputed that argument, saying it doesn't pass muster. “There’s a lot of Monday-[morning] quarterbacking that’s going on,” she said in an interview.

In late September, Republicans appeared resurgent, a product of the pitched battle to confirm Supreme Court Justice Brett Kavanaugh. By late October, their condition soured, the result of a toxic mixture of Trump’s immigration rhetoric, bomb threats against Democrats and media outlets allegedly perpetrated by a Trump supporter, and a mass shooting at a Pittsburgh synagogue that the president fumbled in response.

But Republicans had other problems: chiefly, healthcare.

There has been intense debate — in both parties — regarding the potency of Democratic attacks that charged Republicans, in attempting to repeal Obamacare, would eliminate federal mandates that force insurers to cover pre-existing conditions and prohibit lifetime caps. Senior Republicans now concede the attacks worked.

House Republicans in the spring of 2017 passed legislation partially repealing the Affordable Care Act, which they insist included robust protections for pre-existing conditions. In retrospect, they believe the legislation was politically insufficient, and that they should have held multiple votes on stand-alone proposals to preserve pre-existing conditions.

“We recognized the vulnerability there and actually believed fully in providing pre-existing coverage,” said Rep. Greg Walden of Oregon, who as Energy and Commerce Committee chairman was a key health care negotiator, and as a former National Republican Congressional Committee chairman was keenly aware of the politics of the issue. “I wish it had come up for a vote, and for a lot of reasons, it didn’t.”

The Republican Party netted two seats in the U.S. Senate, increasing its majority to 53. The campaign for Senate unfolded on Trump-friendly turf, but the president delivered. His #MAGA rallies in states that determined Senate control boosted GOP turnout and pushed Republican candidates over the top.

But post-election data compiled by GOP pollster David Winston reveals the extent to which Trump, in highlighting immigration over the economy, sunk his party’s House majority.

As an issue, immigration made independents 59 percent less likely to support GOP candidates, compared to 29 percent more likely; the issues of the border and the caravan, specifically, made independents 47 percent less likely to support Republicans, compared to 28 percent more likely. Independents were 87 percent less likely to support candidates who backed Trump.

“This midterm election will be remembered as a missed opportunity for Republicans with many lingering questions, the most important being: Can Republicans rebuild a majority coalition and regain the House?” Winston said.