House impeachment managers laid out the heart of their abuse-of-power case against President Trump on Thursday — charging that his efforts to pressure Ukraine into political investigations were precisely what the nation’s founders wanted to guard against when they empowered Congress to remove a president from office.

The Democrats also detailed their defense of former vice president Joe Biden’s actions regarding Ukraine in anticipation that it will be a major portion of the White House’s defense later this week, saying Biden’s actions were in line with official U.S. policy at the time and not done to benefit an energy company connected to his son.

But a significant number of Senate Republicans remained unmoved and downplayed the case from House managers, dismissing it as repetitive and unpersuasive as they sought to counter Democrats’ narrative at a time when Trump’s lawyers must stay silent in the Senate Chamber.

House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.), who led the case for Democrats on Thursday, cited “abuse, betrayal and corruption” as not only the offenses that the nation feared the most when they wrote the Constitution, but also those alleged abuses at the core of Trump’s dealings with Ukraine.

“The president’s abuse of power, his betrayal of the national interest, and his corruption of our elections plainly qualify as great and dangerous offenses,” Nadler said. “President Trump has made clear in word and deed that he will persist in such conduct if he is not removed from power.”

During his arguments, Nadler also drew liberally from past comments made by key Trump allies, including Sen. Lindsey O. Graham (R-S.C.), Attorney General William P. Barr and lawyer Alan Dershowitz, who all argued there doesn’t have to be a statutory crime committed to impeach a president.

In one of many video clips played on the Senate floor during the trial, Graham — then serving as a House manager in President Bill Clinton’s 1999 impeachment trial — defined “high crimes” more loosely than he does now as one of Trump’s staunchest defenders.

“It’s just when you start using your office, and you’re acting in a way that hurts people, you’ve committed a high crime,” Graham said on the Senate floor in the clip from 1999. He was not in the chamber Thursday when his quote was played, but later told reporters that the use of his previous comments was “fair game” and recommended the White House do the same with Democrats when Trump’s lawyers begin their defense of the president.

Nadler made a case to the Senate that it would be unreasonable to expect Congress to envision all types of potential presidential corruption and pass laws explicitly forbidding it.

“The Constitution is not a suicide pact,” Nadler said. “It does not leave us stuck with presidents who abuse their power in unforeseen ways that threaten our security and democracy. Until recently, it did not occur to me that our president would call a foreign leader and demand a sham investigation meant to kneecap his political opponents, all in exchange for releasing vital military aid that the president was already required by law to provide.”

Trump was impeached Dec. 18, with Democrats accusing him of withholding nearly $400 million in military aid and a White House visit coveted by Ukraine in exchange for launching investigations into Biden and his son Hunter, as well as a discredited theory that the eastern European nation interfered in the 2016 election. Trump and his counsel have maintained he did nothing improper when he asked Ukrainian leader Volodymyr Zelensky in a July 25 call to probe the two matters.

In addition to the abuse of power charge, Democrats also impeached Trump on a second article of impeachment: that he obstructed congressional attempts to investigate the Ukraine matter.

But the second official day of the House impeachment managers’ arguments centered on the Democrats’ abuse-of-power claims. They will wrap up their case Friday. Trump’s team will launch its defense of the president on Saturday, with the key question of whether the Senate will subpoena new witnesses or documents set to be decided around the middle of next week.

The Senate may only come in for a few hours Saturday morning rather then spending a full day on the trial, in part because Trump did not want much of his defense to be aired on Saturday, when the public may be focused on weekend plans rather than the news, according to a GOP official who like others spoke on the condition of anonymity to discuss the private conversations.

Outside the Senate Chamber on Thursday, GOP senators and the president’s legal team fanned out across the airwaves to push back against the Democrats’ case.

Echoing a comment from several Senate Republicans, Trump attorney Jay Sekulow said “we’re hearing the same things over and over” from the House Democrats.

Meanwhile, even if some Republicans didn’t outright reject the Democrats’ case that there did not need to be an underlying crime for a president to be impeached, most continued to dismiss the overall argument made by the impeachment managers.

“I don’t think that anything they’ve actually alleged — any of the ‘abuses’ — they have actual evidence for,” Sen. Josh Hawley (R-Mo.) said during a break in the trial.

White House officials said Thursday that West Wing aides and Trump’s lawyers will continue to be a frequent presence at the Capitol in the coming days as the president’s team works to defend him. Aggressive public relations and press availabilities are a key part of that strategy, one Republican strategist familiar with the planning said.

“This is going to be more than the president tweeting,” the strategist said, adding that the strategy would include Sekulow addressing the media at microphones set up in the Capitol and Rep. Mark Meadows (R-N.C.) “huddling with 100 reporters” in the hallways.

Trump did tweet Thursday, insisting that Democrats are opposed to a witness deal because they are afraid of what the people called to testify by the GOP would reveal. Democrats have repeatedly said they oppose a witness trade because they believe the witnesses Republicans want are irrelevant to the case.

“The Democrats don’t want a Witness Trade because Shifty Schiff, the Biden’s, the fake Whistleblower (& his lawyer), the second Whistleblower (who vanished after I released the Transcripts), the so-called ‘informer’, & many other Democrat disasters, would be a BIG problem for them!” Trump tweeted.

Though the Republicans’ top desired witness remains Hunter Biden, Graham told reporters Thursday that scrutinizing the former vice president’s son’s service on the board of Burisma, a Ukrainian gas company, would be better handled through the “oversight” process than by calling him as a witness during the impeachment trial.

The Bidens played a prominent role in the House Democrats’ arguments Thursday, as Rep. Sylvia Garcia (D-Tex.), another impeachment manager, sought to debunk the allegations that Joe Biden did anything nefarious in his dealings with Ukraine during his time as vice president.

“The allegations against Biden are completely groundless,” Garcia said, detailing how the former vice president’s efforts to oust the Ukrainian prosecutor general were in line with official U.S. policy and supported by international allies.

But Republican senators said the focus on the Bidens by Democrats made the former vice president and his son fair game for Trump’s defense team.

“It means when President Trump’s lawyers stand up and present their defense, that they are going to have the opportunity to present the very significant evidence that’s supported and still supports a serious investigation into corruption at Burisma and ultimately whether Joe Biden participated in that corruption,” Sen. Ted Cruz (R-Tex.) told reporters Thursday evening.

In 2016, Biden was the Obama administration’s point person on Ukraine policy and led a pressure campaign on the Ukrainian government to fire its top prosecutor, Viktor Shokin, whom the administration believed was not doing enough to root out corruption among Ukraine’s politicians. Shokin had previously investigated Burisma, but Hunter Biden was not accused of any wrongdoing.

Garcia noted that Trump and Republicans didn’t focus on Biden’s actions toward Ukraine until 2019, when “Biden became the front-runner for the Democratic nomination and polls showed that he had the largest head-to-head lead against President Trump. That became a problem.”

She also referenced a letter from Sens. Ron Johnson (R-Wis.), Rob Portman (R-Ohio), Jeanne Shaheen (D-N.H.) and other senators in the Ukraine Caucus to argue that Biden’s desire to see Shokin removed reflected official U.S. policy and was not a sign of personal corruption.

As Garcia spoke, a visibly upset and red-faced Johnson rose from his seat, approached Portman and whispered in his ear. Portman reacted impassively, but his comments did not appear to calm Johnson, who departed the floor for the Republican cloakroom moments later. Johnson, a fierce ally of Trump, said in October that he did not recall signing the letter.

House Intelligence Committee Chairman Adam B. Schiff (D-Calif.), the lead impeachment manager, addressed the other investigation that Trump wanted Zelensky to launch, saying the president floated a “very specific conspiracy theory” that it was Ukraine, not Russia, that hacked the Democratic National Committee and Hillary Clinton’s campaign in 2016 despite there being no evidence to support the claim.

“This theory was brought to you by the Kremlin,” Schiff said. “So we’re not talking about generic interference . . . what Donald Trump wanted investigated or announced, this completely bogus, Kremlin-pushed conspiracy theory.”

Earlier, Garcia played clips of news interviews from FBI director Christopher A. Wray and Tom Bossert, a former homeland security aide at the White House, refuting the Ukraine interference theory.

Before the trial officially began Thursday afternoon, dozens of senators from both parties entered a secure facility in the Senate basement to view a classified document provided by Jennifer Williams, a national security adviser to Vice President Pence.

The document was made available under an agreement between Senate Majority Leader Mitch McConnell (R-Ky.) and Minority Leader Charles E. Schumer (D-N.Y.) announced Wednesday. The document had been previously submitted to the House Intelligence Committee.

Some senators spent only a few minutes in the facility; others stayed for the better part of an hour. Several Democrats emerged to say they didn’t understand why the document had been classified.

“I don’t believe it’s being withheld from the public for national security reasons. It may be withheld for political security reasons,” said Sen. Richard J. Durbin (D-Ill.).

Elise Viebeck, Felicia Sonmez, Colby Itkowitz, Mike DeBonis and Robert Costa contributed to this report.