WASHINGTON >> The lead lawyer for the National Security Council defied a subpoena today to appear before House impeachment investigators, as did other White House witnesses, following President Donald Trump’s orders not to cooperate with the probe.

John Eisenberg and White House aide Robert Blair did not show up for scheduled 9 a.m. interviews in the Democrats’ impeachment inquiry, and two other White House witnesses scheduled for this afternoon, National Security Council aide Michael Ellis and Office of Management and Budget aide Brian McCormack, are also not expected to show, according to a person familiar with the matter who requested anonymity to discuss the confidential interviews. All four witnesses had been subpoenaed.

Democrats want to talk to all four about the machinations inside the White House before and after Trump held a July phone call with Ukrainian President Volodymir Zelenskiy and asked him to pursue investigations into political rival Joe Biden and his family and Ukraine’s involvement in the 2016 election. Eisenberg was instrumental in discussions about how to handle a White House memo recounting the Trump phone call with Ukraine that is central to the impeachment inquiry.

Blair is a top aide to acting White House chief of staff Mick Mulvaney, and McCormack is a former chief of staff to Energy Secretary Rick Perry, who led a U.S. delegation to Ukraine for Zelenskiy’s inauguration in May. Ellis is Eisenberg’s deputy and a former Republican aide to the House intelligence panel.

The three committees leading the impeachment probe informed Ellis and Blair of the subpoenas in letters to their lawyers this morning. In the letters, the heads of the three committees said they had been told by the lawyers that their clients would not appear because a White House lawyer could not be present — one of the points that Trump and Republicans in Congress have used to try and describe the Democrats’ impeachment process as a “sham.”

The heads of the three committees — House Intelligence Committee Chairman Adam Schiff, House Foreign Affairs Chairman Eliot Engel and acting House Oversight and Reform Committee Chairwoman Carolyn Maloney — wrote the lawyers that the argument has no merit and is “the latest in a long line of baseless procedural challenges to the House of Representatives’ authority to fulfill one of its most solemn responsibilities under the Constitution.”

The committees subpoenaed Eisenberg and McCormack last week.

Several more witnesses are scheduled this week, even though the House is on recess. Witnesses called include Perry and former national security adviser John Bolton, but it is unclear if any of them will show up.