The Friday letter from Citizens for Responsibility and Ethics in Washington said that without proper oversight, "our democratic institutions will continue to slip away."
According to the congressional report, Trump administration officials overpaid by about $500 million.
Monday's letter from the House Oversight Committee said the Trump Administration's "wildly exaggerated rumors about Antifa has only served to encourage right-wing militias provoking violence."
The president in recent days, by way of tweet storms and press conferences, has relentlessly bashed the Ukraine whistleblower and denied any wrongdoing during a phone call in which he pressured a foreign leader to investigate a political opponent.
"Hundreds" of new cases have been reported in the past week alone, a top CDC official told lawmakers Tuesday.
The probes comes after media reports accused Chao of using her position in the Trump administration to benefit herself and her family's business.
Betsy DeVos is the eighth Trump administration official the House Oversight Committee found used personal email for government business.
Kellyanne Conway violated the Hatch Act more than a dozen times, the Office of the Special Counsel noted. There were just two violations during the eight years of the Obama administration.
"We are not beyond holding in contempt, sanctioning or even using the Sergeant at Arms to bring someone in," Rep. Stacey Plaskett (D-Virgin Islands) said.
"Once they state something even related to a congressional purpose, the court, I think, will allow this to go through," said Andrew Napolitano, a former judge.
"Every day that we go on without getting to the bottom of this matter is a day that we are putting hundreds, if not potentially thousands, of Americans at risk," the progressive Democrat from New York warned.
"President Trump's actions violate our Constitution's fundamental principle of checks and balances," House Oversight and Reform Committee Chairman Elijah Cummings said.
White House refuses to hand over documents requested by the House Oversight Committee, calling the request "unprecedented and extraordinarily intrusive."
"She is a kind, good person. I respect her greatly, and she did not deserve that," Cohen said during his public testimony on Capitol Hill on Wednesday.
The Republican National Committee mocked Michael Cohen's credibility in a new video shared on Twitter, a day before his appearance before the House Oversight and Reform Committee.
"He's going to say things that will give you chills," a person close to Cohen reportedly said.
"If a review of Mr. Kushner's ethics issues was completed by the White House Counsel, it must be released," Democratic Representative Raja Krishnamoorthi stated.
More than 50 members of the Democratic Women's Working Group have called for a congressional investigation into the president's alleged sexual misconduct.
Donald Trump's former national security adviser didn't receive permission as a former military officer for the 2015 trip, House Oversight chair says.