Senate Minority Leader Chuck Schumer (D-NY) told reporters Tuesday night that if the Justice Department does not appoint a special prosecutor to take over the investigation into Russian interference on Trump’s behalf in the 2016 election, it will indicate that FBI Director James Comey’s sudden termination was “part of a cover up.”

“Were these investigations getting too close to home for the president?” he asked.

Schumer says he questions both the timing of Comey’s firing as well as the reason given by the Justice Department—the mishandling of the investigation into Hillary Clinton’s emails last summer and fall.

“Why now? Why did it happen today?” Schumer asked, noting that if the Clinton missteps were the true reason, the Trump administration could have dismissed him in January.

The leader of the Senate Democrats also expressed fears that the decision would create a chilling effect for next FBI director, who could fear getting fired if they “run afoul of the administration.” He also questioned why Attorney General Jeff Sessions, who publicly recused himself from overseeing the Russia investigation in March, “played a role in firing the man leading it.” Schumer called the decision part of a “deeply troubling pattern,” noting the recent firings of two other top officials involved in investigating the Trump administration: U.S. Attorney for the Southern District of New York Preet Bharara and Acting Attorney General Sally Yates.

Schumer was one of a small handful of officials Trump called personally earlier on Tuesday to give a heads up about Comey’s firing.

“I told him, ‘Mr. President, with all due respect, you are making a big, big mistake,'” Schumer said. “He didn’t really answer.”

Like many of his Democratic colleagues, Schumer is now demanding the appointment of a special prosecutor to take over the Russia investigation Comey was leading at the time of his termination.

“The only way the American people can have faith in this investigation going forward is to have a fearless, independent special prosector,” he said.