"Quite frankly, I don't think they took enough steps to protect the president," Dr. Scott Gottlieb told CNBC.
"It's going to take a long time. I don't know if people are really ready for how long it's going to take," CNBC's Jim Cramer said Monday.
President Donald Trump would not be hurt politically, Mulvaney, now a special envoy to Northern Ireland, told CNBC on Wednesday.
U.S. stock futures were pointing to an advance for the Dow at Wall Street's open on Monday.
Two weeks of explosive public hearings have left lawmakers divided as ever, but House Democrats are charging ahead with the next phase.
The acting chief of staff is expected to be a no-show, falling in line with several other officials who were ordered by the president not to cooperate with the investigation.
U.S. stock futures are modestly higher ahead of Wednesday's open following another day of record highs for the Dow and Nasdaq.
Former Russian analyst Fiona Hill testified to members of Congress on Monday behind closed doors.
"I think it's both bad politically and bad economically and I don't think it's really going to help solve the immigration problem, either," said the former American diplomat.
President Trump says an additional tariff on Mexican goods would address the "border crisis."
White House counsel Pat Cipollone says the documents "remain legally protected from disclosure under longstanding constitutional principles."
Stocks recovered the bulk of their earlier losses on Monday as investors bet China and the U.S. will strike a trade deal despite President Donald Trump's threat to hike tariffs on Chinese imports.
Gold prices dropped to a one-week low on Wednesday as the dollar rebounded after U.S. Federal Reserve reduced expectations of a rate cut this year, with the safe-haven metal also pressured as the central bank signaled strong economic growth.
Stocks in Australia advanced on Wednesday, with most major Asian markets closed for holidays.
The plan, which was rejected twice in the past year, was confirmed to be still in the works by President Donald Trump last week after its existence was first reported by The Washington Post.
NBC's Pete Williams reports that the firing was "not based on any single precipitating event."
Mick Mulvaney, the acting chief of staff, said Sunday that President Donald Trump "is not a white supremacist" and attempts to tie him to the alleged New Zealand mosque shooter are "absurd."
OMB acting director Russell Vought says security at the southern U.S. border is "deteriorating by the day."
"Democrats are harassing the President to distract from their radical agenda of making America a socialist country," the White House says.
It is highly unusual for translators to be hauled in front of Congress, although calls for Democrats to do just that have risen amid an also extraordinary level of secrecy about the president's conversations with Putin.