Congressional Republicans are sticking with their party leader in the face of thousands of pages of evidence showing President Trump leveraged foreign policy for political favors, raising the possibility that not a single House Republican will vote for his impeachment.

As they prepare to hold the first open impeachment hearings this week, Democrats had hoped to peel off Republican support from a key bloc — retiring lawmakers who need not worry about internal blowback or primary challenges.

Yet many are refusing to break with Trump. Rep. Peter T. King of New York made a point of stating his intention to vote against impeaching Trump in his retirement announcement Monday, a troubling sign for Democrats.

Another moderate Republican, Rep. Will Hurd of Texas, sounded like a Trump ally on a Sunday morning talk show as he called for Hunter Biden, son of former vice president Joe Biden, to testify in the impeachment inquiry — an idea being pushed by the White House that concerns some conservative Senate Republicans. Hunter Biden worked on the board of a Ukrainian gas company.

In more than five weeks of testimony, current and former Trump administration officials allege that the president tied foreign aid and a White House meeting to Ukraine’s willingness to announce investigations into the Bidens and a conspiracy theory surrounding the 2016 election. More than a dozen longtime State Department diplomats and National Security Council aides have painted a largely consistent picture of a president adamant on strong-arming a U.S. ally to do his political bidding.

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On Monday, Democrats released the transcript of Laura Cooper’s Oct. 23 closed-door testimony in which the deputy assistant secretary of defense for Russia, Ukraine and Eurasia testified that Trump personally requested that money for Ukraine be frozen. During a July 23 meeting, she said, the Office of Management and Budget told agencies that “the White House chief of staff has conveyed that the president has concerns about Ukraine and Ukraine security assistance.”

Yet Republicans are rallying around the president, including longtime foreign policy hawks such as retiring Rep. Mac Thornberry of Texas. The former House Armed Services Committee chairman and steadfast critic of Russia on Sunday called Trump’s use of foreign aid to elicit a political probe from that nation “inappropriate” but accused Democrats of running a “tainted” and “one-sided” probe.

“There’s a reason we let murderers and robbers and rapists go free when their due process rights have been violated,” Thornberry said on ABC’s “This Week.”

© Seth Wenig/AP President Trump and first lady Melania Trump attend the kickoff for New York City's 100th annual Veterans Day Parade.

GOP cohesion will test Democrats’ impeachment strategy as they moved their inquiry into the public sphere Wednesday. Democrats recognize that the onus is on them to make the case to independent voters who don’t have time to sift through thousands of pages of transcripts alleging presidential misconduct.

If the headlines of the past few weeks have not been enough to move congressional Republicans, however, it’s unclear what — if anything — will. Democrats are unlikely to get Trump’s inner circle, including acting White House chief of staff Mick Mulvaney, to tell their stories publicly before the House votes on articles of impeachment. Former national security adviser John Bolton, who is familiar with relevant meetings and conversations about the pressure on Ukraine, may never testify as he looks to the courts to weigh in on whether he must comply with the investigation, which could take months.

That means Democrats will have to make their case to Republicans on what they have now. The party hopes its public hearings will move Americans further in support of impeachment, putting pressure on moderate Republicans to break with the president. So far, however, the opinion poll numbers favoring impeachment have not convinced even a single Republican in Congress that Trump’s actions are impeachable.

On Monday, Trump was greeted at the New York City Veterans Day Parade with signs of protest. Whistles and chants of “Lock him up!” could be heard from the west side of Madison Square Park on Fifth Avenue near the site of his speech. Reporters also noted that signs spelling out the words “IMPEACH” and “DUMP TRUMP” were posted in the windows of a building overlooking the park.

Trump, who was accompanied by first lady Melania Trump, made no reference to impeachment during his remarks about service members. But he railed against his critics on Twitter, even accusing House Democrats of “doctoring” transcripts of impeachment witnesses without evidence to back up his claim.

Trump has made several demands for how he wants GOP lawmakers to defend him. Over the weekend, Trump insisted that Republicans characterize his July 25 call with Ukrainian President Volodymyr Zelensky as “perfect” — even as many GOP lawmakers took issue with his actions and say it’s clearly a quid pro quo.

“The call to the Ukrainian President was PERFECT,” Trump wrote on Twitter. “Read the Transcript! There was NOTHING said that was in any way wrong. Republicans, don’t be led into the fools trap of saying it was not perfect, but is not impeachable. No, it is much stronger than that. NOTHING WAS DONE WRONG!”

The Democrats’ failure to move GOP lawmakers on impeachment comes despite 20 Republicans announcing their retirement. Only one of those, Rep. Francis Rooney of Florida, has floated the possibility of voting to impeach Trump — but since that declaration, Rooney has voted against the impeachment inquiry as a whole and has gone quiet in his criticism.

The recent rhetoric from Hurd perhaps best highlights the uphill battle Democrats face in winning over retiring GOP members. For years, Hurd, who won in Democratic-leaning districts on the Texas border, has been considered among the most pragmatic members — sometimes voting with Democrats and calling some in his party racist, misogynistic and homophobic.

But during a “Fox News Sunday” interview, Hurd parroted White House talking points, a reflection of how well House GOP leaders are keeping their members in line. Hurd was more critical of the Democrats for their impeachment process than Trump for his pressure on Zelensky, and argued for Hunter Biden’s testimony — a GOP request that Democrats are unlikely to grant.

“I would love to hear from Hunter Biden. I would love to hear from other Americans that served on the board of Burisma,” Hurd said, referring to the natural gas company that paid Biden $50,000 a month to sit on its board while his father was the vice president.

When host Chris Wallace asked Hurd whether pressuring a foreign government to investigate a political rival was “an impeachable offense,” Hurd borrowed from other Trump allies’ playbook: He argued that perhaps Trump was merely going after corruption.

“Well, I don’t know if it was necessarily investigate the Democrats, right? I think it was investigation of corruption,” he said.

In fact, nearly every witness who has appeared before the impeachment inquiry — including Trump appointee and National Security Council official Tim Morrison — has testified that Trump was not looking at corruption generally, something NSC official Fiona Hill called a “code” for going after the Bidens, including the 2020 Democratic presidential candidate. Rather, the probe Trump wanted centered on the Bidens, one that could bolster his reelection bid.

On Monday, former secretary of state Condoleezza Rice, who served under Republican President George W. Bush, said that reports about the shadow policy toward Ukraine were “deeply troubling.”

“What I see right now troubles me,” Rice said at a conference in Abu Dhabi. “I see a state of conflict between the foreign policy professionals and someone who says he’s acting on behalf of the president, but frankly I don’t know if that is the case. . . . It is troubling. It is deeply troubling.”

But “troubling” is not impeachable for some Republicans. That distinction was articulated by Nikki Haley, the former U.S. ambassador to the United Nations, in a Washington Post interview that coincided with the release of her new memoir. Haley said that “it’s not good practice to talk to foreign governments about investigating Americans.” But those actions, she continued, were not impeachable.

“There was no heavy demand insisting that something had to happen. So it’s hard for me to understand where the whole impeachment situation is coming from, because what everybody’s up in arms about didn’t happen,” Haley said, later adding: “Do I think the president did something that warrants impeachment? No, because the aid flowed.”

rachael.bade@washpost.com