Told that the White House denied being the source of the leak, Pelosi responded, "I rest my case."
In a statement released by her office earlier Friday, spokesman Drew Hammill said:
"In the middle of the night, the State Department's Diplomatic Security Service provided an updated threat assessment detailing that the President announcing this sensitive travel had significantly increased the danger to the delegation and to the troops, security, and other officials supporting the trip," continued Hammill. "This morning, we learned that the Administration had leaked the commercial travel plans as well."
The White House, in a statement released on background, called the charge "a flat out lie."
"When the Speaker of the house and about 20 others from Capitol Hill decide to book their own commercial flights to Afghanistan, the world is going to find out. The idea we would leak anything that would put the safety and security of any American at risk is a flat out lie," the statement said.
Later, White House press secretary Sarah Sanders elaborated. "It is outrageous that she would accuse the president of the United States of putting any life in jeopardy," Sanders said. "In fact the reason he didn't want her to go is because he's trying to protect American citizens. He wants to secure our border. And he wants a solution and he wants her to stay here to help him fix it."
Hammill said that "in light of the grave threats caused by the President's action, the delegation has decided to postpone the trip so as not to further endanger our troops and security personnel, or the other travelers on the flights."
He posted a similar response on Twitter after a White House reporter cited an administration official saying claims about the leak were a lie.