WASHINGTON (AP) — House Republicans on Thursday are holding the first hearing of their impeachment inquiry into President Joe Biden and their effort to tie the him to the business dealings to his son Hunter.

It’s a high-stakes opening act for Republicans as they begin a process that can lead to the ultimate penalty for a president, punishment for what the Constitution describes as “high crimes and misdemeanors.”

Rep. James Comer, chairman of the House Oversight and Accountability Committee, said the committee had “uncovered a mountain of evidence” that he said would show how the Democratic president abused his power and repeatedly lied about a “wall” between his political position and his son’s private business dealings. “There was no wall,” Comer said.

Republicans have been investigating Hunter Biden for years, since his father was vice president. While questions have arisen about the ethics surrounding the Biden family’s international business, no evidence has emerged so far to prove that Joe Biden, in his current or previous office, abused his role or accepted bribes.

House lawmakers are facing a resistance in the Senate from Republicans who are worried about the political ramifications of another impeachment and who say Biden’s conviction and removal from office is a near impossibility.

Some takeaways from the opening hearing:

Republicans called Georgetown law professor Jonathan Turley as an expert witness. He is a staple of impeachment proceedings, having testified in support of the 1998 impeachment proceedings against President Bill Clinton and against the first of two impeachment cases against President Donald Trump.

Turley said he did not believe the evidence so far supported bringing articles of impeachment against Biden. But Turley said the threshold had been met to launch an inquiry. To support his position, he asserted that Biden had made “demonstrably untrue” statements about business deals and had been the focus of a “multimillion-dollar” influence-peddling effort.

Democrats countered with testimony from Michael Gerhardt, a University of North Carolina law professor, who also has a long history on impeachment issues. He testified during Trump's first impeachment. In 1998, Gerhardt was called as a joint witness, by Democrats and Republicans, to testify on impeachment.

Gerhardt said he had heard no evidence for impeachment charges against the president.

"Any further investigation is being done to ensure that Mr. Biden has to prove his innocence rather than rather than the committee being able to connect the dots in a convincing and persuasive way,” Gerhardt said in his opening statement. “It’s not me you have to persuade. It’s the American people whose trust you deserve and whose trust you have to maintain.”

The inquiry is opening as the federal government is days away from a shutdown that would halt paychecks for millions of federal workers and the military.

It’s the responsibility of Congress to fund the government. The House and Senate have to agree to fund the government and the president has to sign that legislation into law.

A shutdown will effectively begin at 12:01 a.m. Sunday without action on Capitol Hill, and lawmakers are nowhere near a deal.

As the hearing began, Democrats displayed a screen showing the days, hours and minutes left until the government would shut down. They questioned the priorities of House Republicans, who hold a slim majority, as they struggle to pass any funding bills.

“We’re 62 hours away from shutting down the government of the United States of America and Republicans are launching an impeachment drive, based on a long debunked and discredited lie,” said Maryland Rep. Jamie Raskin, the top Democrat on the committee, in his opening statement.

As the hearing got underway, the president was in Arizona, readying to give an address on the state of democracy as the 2024 election draws near. It's a core focus of his reelection campaign that is becoming increasingly intertwined with the political dynamics around him.

Trump, his likeliest Republican opponent, continues to spread falsehoods about the results from the 2020 election that he lost to Biden and is battling unprecedented criminal charges stemming in part from those lies. Some members of the House committees investigating the Bidens also spread the falsehoods. Biden has increasingly called out Trump by name and this week said the former president and his supporters were seeking to destroy American democracy.

With the impeachment inquiry and investigations into Biden's son, Trump's supporters in the House are seeking in part to refocus the spotlight around the Biden family and away from Trump's criminal indictments.

Hunter Biden has been the target of Donald Trump and Republicans for years. He's now fighting back.

This week, he sued Rudy Giuliani and another lawyer, accusing them of obtaining, trading and passing around his private data including purported emails and embarrassing images in their effort to discredit his father.

Hunter Biden's lawyers say Trump's allies spent years “hacking into, tampering with, manipulating, copying, disseminating, and generally obsessing over” the data that was “taken or stolen” from Biden’s devices or storage, leading to the “total annihilation” of Biden’s digital privacy.

Over the past few months, Hunter Biden has sued a former aide to Trump over his alleged role in publishing emails and embarrassing images, and filed a lawsuit against the IRS saying his personal data was wrongly shared by two agents who testified as whistleblowers as part of the impeachment investigation by House Republicans.