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WASHINGTON (NEXSTAR) — As a former national deputy security adviser failed to show up for closed-door questioning in House Democrats’ impeachment inquiry, Republicans are still condemning the process.

Charles Kupperman didn’t appear for his scheduled meeting Monday morning with the House Intelligence Committee, Rep. Adam Schiff, D-Calif., said.

“He was a no-show. This is deeply regrettable,” Schiff, who chairs the committee, told reporters. “He was compelled to appear by lawful congressional subpoena. … Nonetheless, we move forward.”

Schiff called it a “desperate tactic” by the White House. President Donald Trump has ordered witnesses to skip testimonies, calling the inquiry illegitimate and unfair. Senate Republicans are backing him.

“So far, everything in the House of Representatives has been done in absolute secrecy,” Sen. Chuck Grassley, R-Iowa, said.

He was among 50 Republicans who backed a resolution condemning Democrats for a lack of transparency and questionable leaks.

“If it makes him (Trump) look bad, they gets out,” Grassley said, adding that leaked information can’t be trusted as accurate.

His colleague, Sen. Roy Blunt, R-Mo., said the investigation needs to be brought into the light.

‘You have to have a public hearing that everyone has equal access to the background information,” he said.

But Schiff defended the process and questioned Republicans’ reasons for objecting.

“Where is their duty to this institution?” he demanded. “Where is their duty to the Constitution?”

The House has scheduled five more closed-door depositions for this week as it digs into Trump’s dealing with Ukraine. Schiff said public hearing will be held soon, but refused to give a precise timeline.

Kupperman could be held in contempt for not complying with the subpoena.