The U.S. Congress should revisit proposed legislation to protect special counsel Robert Mueller after President Donald Trump tried to fire him last year while he investigated the Trump campaign's ties with Russia, two Republican senators said on Sunday.

In separate television interviews, Sens. Susan Collins and Lindsey Graham expressed dismay at reports the Republican president had told the top White House lawyer to order U.S. Justice Department officials to fire Mueller.

"I've got legislation protecting Mr. Mueller, and I'd be glad to pass it tomorrow," Graham told the ABC News "This Week" program.