After two weeks of public testimony that President Trump politicized Ukraine policy and leveraged taxpayer dollars for his own benefit, there is no sign that any Republicans will defect and vote to impeach Trump in the House, much less convict him in the Senate.

On the contrary, Republicans are backing the president up by launching a counterinvestigation in the Senate into the Biden family, the very thing Trump wanted Ukraine to announce it’s investigating. And some of the most moderate House Republicans, such as Rep. Will Hurd (Tex.) or Brian Fitzpatrick (Pa.), aren’t even considering voting for impeachment, based on their public remarks. It’s entirely possible Trump gets impeached by the House with only Democratic votes.

That’s a remarkable display of unity by Republicans, one that helps strengthen Trump’s case that impeachment is a partisan exercise — and ensures that Senate Republicans who might defect, if there are any, have to step out on their own.

But why? I talked to Republican strategists, pollsters and an academic, and we came up with a few not mutually exclusive theories for why Republican lawmakers are so loyal to Trump, even in the face of evidence of wrongdoing.

Republican voters are loyal to him

The president’s approval ratings have remained largely static throughout controversies — about 40 percent overall, but 80 to 90 percent of Republican voters approve of the job he’s doing — and indications are that impeachment is no different.

A CNN poll taken as the hearings were wrapping up last week found 10 percent of Republicans saying Trump should be impeached and removed from office, while 89 percent of Republicans approved of the job he’s doing.

There’s a reason Trump has commanded such loyalty, pollster Glen Bolger said. He’s a singular politician, and voters chose him precisely because of who he is.

“When you talk to grass-roots Republicans, they will say: ‘Look, we are not happy with everything he’s doing. He tweets too much.’ But they say, ‘We are glad we have somebody who fights.’ … Republicans looked up at him and said, ‘He’s the anti-McCain, he’s the anti-Romney, and he’s just what we need.’ ”

Strategist Doug Heye said: “Outside of D.C., everybody has basically made up their mind on Trump. There are persuadable people, but it’s a pretty small number. On the Republican side they are all in. Period.”

Against that backdrop, it would be extremely risky for Republicans to acknowledge wrongdoing by Trump, much less that he should be impeached, said Matt Green, who studies Congress and polarization at Catholic University.

“If you’re a Republican in a conservative district,” Green said, “it’s politically very risky to endorse impeachment. You’re going to have a lot of angry voters and a primary challenger.”

Republican lawmakers need him

Money. The ability to shape policy with someone who thinks like you. A tweet in support of your reelection. There are tangible benefits to being aligned with the president that you lose if you ditch him.

That’s particularly true for the minority party in Congress, Green said. Republicans can’t control the process in the House anymore after losing it in the 2018 midterms. So having an ally in the White House is especially important to them.

“While becoming a majority is the number one goal of a minority party, protecting the presidential party” is right up there, Green wrote in the politics blog Mischiefs of Faction.

“It’s not like Trump is going to lose his Twitter account if he’s impeached,” Green added in an interview with The Fix.

They don’t think Trump deserves impeachment

Green said there are Republicans who are genuinely frustrated by the process of the inquiry, especially that Democrats leaked damaging testimony during the closed-door sessions to frame the narrative that Trump was wrong. And that Democrats have overruled Republicans on calling certain witnesses beneficial to Trump.

There are also Republicans who honestly think that what Trump did might have been wrong but doesn’t rise to deserving of impeachment, especially less than a year before voters will get to decide.

“Who are we not hearing from?” Fitzpatrick, a moderate Republican, told NBC Philadelphia. “I would call it poor judgment, for sure,” he said when asked whether he thought Trump had abused his power.

The facts we have so far all point to Trump having done what the whistleblower and Democrats allege. But it’s up to members of Congress to determine whether that is worthy of impeachment. Combine the wiggle room the Constitution affords them with their frustration over how Democrats have conducted the inquiry, and some Republicans have all the justification they need to stay in line with Trump.

It’s really dramatic to vote to impeach your party’s president

Setting aside Trump’s commanding persona and all the ways he can help Republican lawmakers, impeachment is an extremely serious thing. It’s the last resort in the Constitution for dealing with unruly presidents. And thus far in U.S. history, impeachment proceedings have never been led by the party of the president.

In the modern era, it’s rare for members of a party to vote to impeach a president of the same party. Of the five Democrats who voted for Bill Clinton’s impeachment, three eventually became Republicans.

“My judgment so far as an objective observer is that there are multiple actions on this president’s part that warrant a vote of impeachment in the House,” wrote former Republican senator Slade Gorton in a New York Times column urging his fellow Republicans to impeach Trump. Gorton supported Nixon’s resignation, but, notably, he was a state official and not in the Senate during impeachment.

This era is hyperpartisan. Polarization means your side is good and the other side is bad, pollster Bolger said. “If that’s the mind-set, there’s no reason to think Republican voters will tolerate impeachment.”

Especially given the timing.

Republicans turning on Trump would throw their party into turmoil before elections in which the White House and control of Congress is at stake.

Everyone to whom The Fix talked for this report said they don’t expect any change in Trump’s support in the House until his support among Republican base voters starts to erode. And no one could foresee an event that would cause that to happen.