Trump released Bannon from the privilege in a Saturday letter to Costello, saying: "If you reach an agreement on a time and place for your testimony, I will waive executive privilege for you, which will allow for you to in and testify truthfully and fairly as per the request of the Unselect Committee of political Thugs and Hacks."
Rep. Zoe Lofgren, D-Calif. and a committee member, said Sunday on CNN's "State of the Union that the committee expects to hear from Bannon soon.
"And there are many questions that we have for him," she said.
In recent days, as the former president grew frustrated with what he decried as a one-sided presentation by the committee of seven Democrats and two Republicans, Trump said he would waive that privilege claim, according to a letter Saturday to Bannon's lawyer.