House Democrats launched into marathon arguments in President Donald Trump’s impeachment trial Wednesday, appealing to skeptical Republican senators to join them in voting to oust Trump from office to “protect our democracy.”

Led by U.S. Rep. Adam Schiff of California, impeachment managers have two more days — Thursday and Friday — to convince 67 U.S. senators that President Donald Trump should be removed from office.

Watch the trial live here.

On Wednesday, Trump’s lawyers sat by, waiting their turn, as the president blasted the proceedings from afar, threatening jokingly to face off with the Democrats by coming to “sit right in the front row and stare at their corrupt faces.”

Schiff, chairman of the House Intelligence Committee and lead House impeachment prosecutor, outlined what Democrats contend was the president’s “corrupt scheme” to abuse his presidential power and then obstruct Congress’ investigation. He then called on senators not to be “cynical” about politics, but to draw on the intent of the nation’s Founding Fathers who provided the remedy of impeachment.

“Over the coming days, we will present to you—and to the American people—the extensive evidence collected during the House’s impeachment inquiry into the president’s abuse of power,” said Schiff standing before the Senate. “You will hear their testimony at the same time as the American people. That is, if you will allow it.”

Democrats proposed 10 amendments during the marathon session, and Republicans rejected all of them. At nearly 2 a.m. Wednesday, the Senate approved the rules 53-47, reflecting the Republican-Democratic makeup of the chamber.

Chief Justice John Roberts gaveled open Wednesday’s session as senators settled in for the long days ahead.

Trump, who was in Davos, Switzerland, attending a global economic forum, praised his legal team, and suggested he would be open to his advisers testifying, though that seems unlikely. He said here were “national security” concerns that would stand in the way.

»Track your U.S. senator on President Trump’s impeachment trial

After the House prosecutors present their case, the president’s lawyers will follow with another 24 hours over three days. They are expected to take only Sunday off.

“There’s a lot of things I’d like to rebut,” said Trump lawyer Jay Sekulow at the Capitol, “and we will rebut.”

John Roberts serves as the 17th Chief Justice of the United States. He was born in Buffalo, N.Y., and grew up in the Midwest. He completed his undergraduate degree at Harvard and then attended Harvard Law School, graduating with a law degree in 1979. Roberts worked as a clerk during his early legal career, then went into private practice, arguing 39 cases before the Supreme Court. Roberts was appointed to the U.S. Court of Appeals in 2003. President George W. Bush nominated Roberts to the Supreme Court af

Then there will be 16 hours for senators to ask written questions, and another four hours for deliberations.

After more than 12 hours of contentious speechifying and an admonishment from the chief justice of the U.S. Supreme Court himself, the Senate approved the rules for Trump’s trial on Tuesday.

The trial is now on a fast-track with almost no signs of Republican resistance to the actions that led to his impeachment.

“It’s about time we bring this power trip in for a landing,” said White House counsel Pat Cipollone, the president’s lead lawyer, lashing out at the House Democrats prosecuting the case.

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Republicans turned back Democratic amendments to subpoena documents from the White House, State Department, Defense Department and budget office. By the same 53-47 party-line, they turned away witnesses with front-row seats to Trump’s actions including acting White House chief of staff Mick Mulvaney and John Bolton, the former national security adviser critical of the Ukraine policy.

The U.S. Constitution requires a two-thirds majority in the Senate (or 67 senators) to convict in an impeachment trial.

Republicans hold 53 seats in the Senate, while Democrats hold 45. However, two Independents — including presidential candidate Bernie Sanders of Vermont — regularly caucus with Democrats, giving the nation’s blue party 47 votes.

If the Senate votes along party lines regarding impeachment — as did the House — 20 Republican senators would have to join Democrats in voting to remove the nation's 45th president from office.

Here are the key figures in President Donald Trump's impeachment trial. House Speaker Nancy Pelosi. She led the impeachment effort. Chief Justice John Roberts. He will preside over the trial. The Senate's political leaders - Majority Leader Mitch McConnell and Minority Leader Chuck Schumer. The president's legal defense team - White House counsel Pat Cipollone, Trump personal lawyer Jay Sekulow, Kenneth W. Starr, Alan Dershowitz, along with Robert Ray and Jane Raskin. House Democratic impeachment managers

The White House legal team did not dispute Trump’s actions, when he called Ukraine and asked for a “favor,” which was to investigate Democrat Joe Biden as the U.S. was withholding military aid the ally desperately needed as it faced off with hostile Russia on its border. But the lawyers insisted the president did nothing wrong.

McConnell stunned senators and delayed the start of proceedings with his decision to back off some of his proposed rules. He made the adjustment after encountering resistance from Republicans during a closed-door lunch meeting. Senators worried about the political optics of "dark of night" sessions that could come from cramming the 24 hours of opening arguments from each side into just two days.

Impeachment was established in the U.S. Constitution as a way to accuse a president of a crime and then hold a trial to determine if guilty. The first step requires a U.S. House member to introduce an impeachment resolution. The House speaker directs the judiciary committee to hold a hearing to decide whether to put the full measure to a vote by the full chamber. A majority of the committee must approve the resolution. If approved, it moves to a full vote on the House floor. If a majority of the House vot

The two articles of impeachment passed by House Democrats last month charge the nation’s 45th president with high crimes and misdemeanors.

»MORE: Which U.S. presidents have faced impeachment?

The first article of impeachment charges President Trump with abuse of power.

Democrats allege Trump “solicited the interference of a foreign government, Ukraine, in the 2020 U.S. presidential election. He did so through a scheme or course of conduct that included soliciting the government of Ukraine to publicly announce investigations that would benefit his reelection, harm the election prospects of a political opponent, and influence the 2020 U.S. president election to his advantage.”

The “election prospects of a political opponent” refer to former Vice President Joe Biden, currently the front-runner in the still-crowded field of Democratic White House hopefuls.

House Speaker Nancy Pelosi has named seven impeachment managers for President Donald Trump's upcoming Senate trial: U.S. Rep. Adam Schiff of California, chair of the House Intelligence Committee, and lead manager U.S. Rep. Jerrold Nadler of New York, chair of the House Judiciary Committee U.S. Rep. Zoe Lofgren of California U.S. Rep. Hakeem Jeffries of New York U.S. Rep. Val Demings of Florida U.S. Rep. Jason Crow of Colorado U.S. Rep. Sylvia Garcia of Texas Senate Majority Leader Mitch McConnell expects

The president “also sought to pressure the government of Ukraine to take these steps by conditioning official U.S. government acts of significant value to Ukraine on its public announcement of investigations.”

Democrats argue the president “used the powers of his presidency in a manner that compromised the national security of the United States and undermined the integrity of the United States democratic process. He thus ignored and injured the interests of the nation.”

In the second article of impeachment, titled obstruction of Congress, Democrats charge Trump has defied House subpoenas as it has pursued its constitutional power of impeachment.

»RELATED: Pelosi OKs articles of impeachment against President Trump

“As part of this impeachment inquiry, the committees undertaking this investigation served subpoenas seeking document and testimony deemed vital to the inquiry from various executive branch agencies and offices,” the articles read. “President Trump directed executive branch agencies, offices and officials not to comply with those subpoenas.

“These actions were consistent with President Trump’s previous efforts to undermine U.S. government investigations into foreign interference in United States elections.”

The Associated Press contributed to this report.