Sen. Amy Klobuchar (D-MN) called President Donald Trump’s impeachment proceedings “a global Watergate” during the Thursday night Democrat debate at Loyola Marymount University in Los Angeles, California.

“This is a global Watergate,” Klobuchar said, arguing that Trump, like former President Richard Nixon in the case of the Watergate scandal of the 1970s, was a “paranoid president who looked for dirt on a political opponent.”

“He did it by getting people to break in. This president did it by calling a political leader to look for dirt on a political opponent,” Klobuchar said of Trump’s dealings with Ukraine.

“We should be hearing from Mulvaney,” Klobuchar said, referring to Trump’s chief of staff Mick Mulvaney, while calling for other staff to testify under oath at the Senate impeachment trial.

“If President Trump thinks he should not be impeached, he should not be scared to put forward his own witnesses,” she added.

The House of Representatives voted on Wednesday to pass two articles of impeachment against the president. The first was abuse of power, and the second was obstruction of Congress, both over Trump’s dealings with Ukraine.

The partisan division between the House and the Senate comes as the Senate decides whether to pressure the White House to send witnesses to testify under oath. The GOP says no witnesses are necessary, while Democrats like Klobuchar say they are necessary for a fair trial.