President Donald Trump’s feuds with Democratic leaders regularly make news, but away from the spotlight he may have more to fear from the work of long-serving Rep. Elijah Cummings.

The President’s Day weekend was bookended by two bombshells from the Maryland Democrat’s House Oversight Committee on Trump’s affair with porn star Stormy Daniels and the Administration’s relationship with Saudi Arabia.

On Friday, the committee released evidence that two of Trump’s attorneys, Sherri Dillon and Stefan Passantino, may have lied to officials at the Office of Government Ethics about reimbursements to Michael Cohen for keeping Daniels quiet. On Tuesday, it released a report alleging that key Trump Administration officials had tried to rush a transfer of nuclear technology to Saudi Arabia.

“They are pulling the veil off of some very significant investigations that many of us didn’t even appreciate were there,” said Austin Evers, the Executive Director of the watchdog group American Oversight, of the Democrats on the oversight committee.

In an interview with TIME this past December, Cummings emphasized that a key part of his role as chairman was to fulfill the constitutional mandate to be a check on the President. As a result, he said, he planned to hold the Administration accountable for any corruption that had gone unchecked when Republicans were in charge of the House. “I am not here to make headlines,” he said. “I am here to get people’s problems solved.”

Veterans of the oversight committee say Cummings’ methodical and understated approach to investigating the Trump Administration is in line with the way he has conducted himself throughout his tenure in Congress. “His word was his bond,” said his former Republican Rep. Tom Davis, who previously chaired the oversight committee. “If he made a deal he knew how to keep a deal.”

Davis also noted that the reports Cummings has produced are indicative of the way the oversight committee is expected to to do its job, even if they lack the theatrics of Congressional hearings that generally garner more attention. “It’s not in the public spotlight, but you get more substance out of the reports,” he explained.

While the evidence in the report about Saudi Arabia reflects another way administration officials may have blurred the line between business and politics, it also illuminates another challenge the Trump Administration faces with a Democratic-controlled Congress: the threat from “whistleblowers.” It was people working inside the White House who were were alarmed by these actions and took their concerns to Congress which led to the report.

“[The whistleblowers] have warned of conflicts of interest among top White House advisers that could implicate federal criminal statutes,” the report reads. “They have also warned about a working environment inside the White House marked by chaos, dysfunction and backbiting. And they have warned about political appointees ignoring directives from top ethics advisers at the White House who repeatedly and unsuccessfully ordered senior Trump Administration officials to halt their efforts.”

It is these admissions, say Kurt Bardella, a former Republican staffer on the committee who now identifies as a Democrat, that should worry the White House the most. These officials would never have felt comfortable bringing these grievances to a Republican-led majority, Bardella said, but the change of power offered them a safe space where they knew they could get answers. (Cummings noted that he had attempted to pursue such avenues of inquiry two years ago, but was promptly shut down by Republicans.)

“One of the understated consequences of the new Democratic majority was that for the first time during the Trump Administration there was going be a place for government whistleblowers to turn to and provide information to Congress in a way that would result in actionable oversight,” said Bardella. “Whistleblowers can be the one thing Trump can’t control that would have a profound impact on this Administration.”

Cummings’ office declined to say what was coming up on their agenda, pointing instead to the public hearing schedule. (Commerce Secretary Wilbur Ross is slated to testify before the committee on March 14, where he will be grilled about including a question about citizenship on the 2020 census). And the White House is also now facing several deadlines for document requests. Acting White House Chief of Staff Mick Mulvaney has until March 5 to produce documents from the past two years about the plan to transfer nuclear technology. Alan Futerfas, attorney for the Trump organization, has until Feb. 22 to provide documents about the payments to Cohen, which Cummings said in a letter the organization had previously ignored. And White House Counsel Pat Cipollone has until Feb. 22 to provide the documents the committee requested about Trump’s payments to Cohen.

Explicitly unstated in those letters is that a failure to comply with these requests could produce subpoenas, forcing legal adherence.

“If I were the Trump Administration these would be alarm bells,” said Evers. “[…] the oversight committee is way out ahead of any defensive oversight posture the administration might have thought it was already in.”

Write to Alana Abramson at Alana.Abramson@time.com.