The White House late Tuesday afternoon told the House of Representatives it will refuse to cooperate with the impeachment inquiry, calling it unconstitutional and illegal.

It comes after President Donald Trump blocked the U.S. ambassador to the European Union from testifying before multiple House committees.

“I feel a sense of panic in the White House,” said Rep. Mike Quigley, a Democrat who represents Illinois’ 5th Congressional District, on CNN. “For the first time, the public mood about this has changed. For the first time, it’s not just smoke, it’s the fire that the public can see, and I think the president’s reacting as such.”

Asked whether the House would subpoena Gordon Sondland, the ambassador whom Trump stopped from testifying, Quigley said it’s a likely step but he’s optimistic that witnesses in the impeachment inquiry will still appear before Congress.

“I'm an optimistic guy – after all, I'm a Cub fan,” Quigley said. “I’ll be here ready to go, because that’s my job. I hope that they believe in the constitution as much as I do.”

As for if and when congressional Republicans – particularly Senators, who would vote on Trump’s potential removal from office – will ever break with the president, Quigley didn’t predict any major swings.

“I think we’ve seen cracks and fissures, first with the president’s foreign policy decisions (on Syria). I think we saw it last week as well when the Senate said unanimously that (the White House) had to turn over the whistleblower’s complaint,” Quigley said during an appearance on “Chicago Tonight.” “But ... too often we see these profiles in courage come from Republicans who are either gone from Congress or about to leave. Now’s the time for them to step up, on his foreign policy decisions, on (his) attack on the rule of law.”

Related stories:

White House Fighting Impeachment by Stalling and Attacking

Depositions and More: What to Watch on Impeachment This Week

White House Prepares Formal Objection to Impeachment Probe