WASHINGTON — President Donald Trump on Monday doubled down on his decision to leave Democrats in the dark about the raid on the Islamic State militant group's leader, Abu Bakr al-Baghdadi, saying he believed at least one top Democrat could leak the plans.

When asked by a reporter why he didn't inform House Speaker Nancy Pelosi of the military action, Trump attacked House Intelligence Committee Chairman Adam Schiff, who has been leading the Democrats' impeachment inquiry, suggesting the California congressman could have done something that would have put American lives at risk.

"I think Adam Schiff is the biggest leaker in Washington," Trump said before boarding Air Force One for a trip to Chicago. "You know that, I know that, we all know that. I've watched Adam Schiff leak. He's a corrupt politician, he’s a leaker like nobody’s ever seen before."

While Trump kept the plans secret from Democrats, he informed a number of top Republican allies and foreign governments. Pelosi accused Trump yesterday of informing the Russians before the Democrats, and Senate Minority Leader Chuck Schumer, who said he learned about the raid on television, has called on the White House to provide a full briefing.

The lack of notice to congressional leaders, which marked a break with precedent, came as the presidential impeachment inquiry marches forward.

Trump said Sunday when he announced al-Baghdadi's killing that he had not told Democrats of the plans because "I wanted to make sure this kept secret, I didn't want to have men lost, and women, I didn't want people lost."

While the president is not required to notify congressional leaders on both sides of the aisle, it has been standard practice: President Barack Obama, for example, had that group briefed ahead of the raid that resulted in the death of al Qaeda leader Osama bin Laden, and called former President George W. Bush before his public remarks on that event.