Michael Chertoff, who was one the lead prosecutor on the Senate’s Whitewater committee that pursued the Clintons in the 1990s, has officially endorsed Hillary Clinton’s campaign for the White House.

The Whitewater scandal centered around Bill and Hillary Clinton’s real estate investments in Arkansas. The Clintons and Chertoff have long been political foes, but in an interview with Bloomberg, the former Secretary of Homeland Security said Clinton’s “mistakes”—from Whitewater to using a private email server as Secretary of State—pale in comparison to the larger issue of national security and do not disqualify her for the White House.

“People can go back decades and perhaps criticize some of the judgments that were made,” Chertoff said. “That is very, very insignificant compared to the fundamental issue of how to protect the country.”

Chertoff has been publicly critical of Republican nominee Donald Trump in the past, signing on to a letter that said Trump would be “reckless” as commander-in-chief. Chertoff mocked Trump’s performance in the first presidential debate, and the aftermath.

For more on the 2016 presidential debate, watch this Fortune video:

“Not only did he seem at the debate to lose his temper, but to get up at 3:30 a.m. and reac h for your smartphone is to me a hysterical reaction,” he said. “If you’re president, the button you reach for is not the Twitter button; it’s the nuclear button.”