(From L) Democratic presidential hopefuls, entrepreneur Andrew Yang, Mayor of South Bend, Indiana Pete Buttigieg, Massachusetts Senator Elizabeth Warren, former Vice President Joe Biden, Vermont Senator Bernie Sanders, Minnesota Senator Amy Klobuchar and businessman Tom Steyer participate of the sixth Democratic primary debate of the 2020 presidential campaign season co-hosted by PBS NewsHour & Politico at Loyola Marymount University in Los Angeles, California on December 19, 2019.

Democratic presidential candidates used an opportunity Thursday night to take a question about President Donald Trump's impeachment as a chance to make the case for their presidency run.

Sen. Elizabeth Warren said that to defeat Trump, America needed a candidate who "can draw the sharpest distinction between the corruption of the Trump admin and a Democrat who is willing to get out and fight."

Warren, who has based much of her campaign on addressing U.S. economic inequality, further highlighted Trump's policies that she believes benefit the largely rich.

"This president has made corruption originally his argument, that he would drain the swamp. And yet he came to Washington, broke that promise and has done everything he can for the wealthy and the well connected."

Former Vice President Joe Biden and Sen. Amy Klobuchar took a different approach, focusing instead on their more moderate positions.

A senior Biden campaign official told CNBC prior to the debate that the vice president would spend the evening focused on his case against Trump, emphasizing that he is the candidate in the best position to beat him.

Biden during the debate complained foreign leaders are viewed more favorably than the president of the United States, adding, "We need to restore the integrity of the presidency, of the office of the presidency."

Billionaire Tom Steyer shifted the conversation to the upcoming impeachment trial in the Senate, saying the witnesses the White House has prohibited from testifying should be called up. Senate Minority Leader Chuck Schumer has demanded that Majority Leader Mitch McConnell call administration officials, including Acting Chief of staff Mick Mulvaney and former National Security Advisor John Bolton, to the witness stand.

"If we want the American people to understand what's going on, we need to have the administration officials testify on television so we can judge," Steyer said during the debate. "The American people deserve to see the truth of these administrative people under oath so we can make up our mind."

Entrepreneur Andrew Yang broke with his rivals, saying Democrats must stop focusing on Trump and try to explain how they will make life better for the average voter.

"The more we act like Donald Trump is the cause of all our problems, the more Americans lose trust that we can actually see what's going on in those communities and solve those problems," he said.

"We have to stop being obsessed with impeachment, which unfortunately strikes many Americans as a ball game when you know what the score is going to be, and start digging in and solve all the problems that got Donald Trump elected in the first place."