House Democrats are continuing to block testimony from about a dozen witnesses who sought to appear before the intelligence oversight panel investigating Russian interference in the 2016 election.

Congressional officials said one of the key witnesses, former informal adviser to the Trump campaign Carter Page, was scheduled to testify at a closed hearing of the House Permanent Select Committee on Intelligence.

But Democrats on the committee blocked the testimony, asserting they needed more time to prepare.

“He’s the guy that many Democrats have been pointing to as the supposed mastermind and you would think they were interested hearing his story,” said one Capitol Hill official.