The incoming president and the current federal office of ethics openly clashed Saturday, in a battle that sets up a heated debate over how much the Senate should know about cabinet nominees ahead of their hearings.

The independent Office of Government Ethics expressed “great concern” that several of President-elect Donald Trump’s cabinet nominees have not yet completed the required ethics review process or even filed any financial information but face confirmation hearings in the next week.

A Senate Democratic aide told NewsHour that four upcoming nominees have not cleared the ethics process yet: Ben Carson, Housing and Urban Development; Betsy DeVos, Education; John Kelly, Homeland Security; and Wilbur Ross, Commerce.

A Republican aide on the Senate Health, Education, Labor and Pensions (HELP) Committee confirmed the DeVos has not yet completed the OGE ethics process. Her hearing is one of the first, scheduled for Wednesday at 10 a.m. The NewsHour reached out to all committees involved and received no other direct responses on nominees’ ethics status.

The Trump transition team also declined to address individual nominees, but pushed back strongly against the federal ethics office, accusing it of playing politics.

“President-elect Trump is putting together the most qualified administration in history and the transition process is currently running smoothly,” wrote Trump transition spokeswoman Jessica Ditto in an email. “In the midst of a historic election where Americans voted to drain the swamp, it is disappointing some have chosen to politicize the process in order to distract from important issues facing our country. This is a disservice to the country and is exactly why voters chose Donald J. Trump as their next president.”

The concerns came in a Friday letter from Walter Shaub, the director of the Office of Government Ethics, who was responding to questions from top Democrats in the Senate. Senate Democratic Leader Chuck Schumer released the letter Saturday.

“The announced hearing schedule for several nominees who have not completed the ethics review process is of great concern to me,” Shaub wrote. “I am not aware of any occasion in the four decades since OGE was established when the Senate held a confirmation hearing before the nominee had completed the ethics review process.”

Senate confirmation hearings are set to begin Tuesday, with 10 nominees scheduled to go before various Senate panels next week.

OGE director Shaub argued that federal law requires that ethics reports be completed before any hearings take place.

But Senate Republicans disagree.

The spokesperson for the Republican majority on the HELP committee, Margaret Atkinson, insisted that clearance of the ethics process is not a requirement before hearings start.

“Our committee precedent is that we require the OGE paperwork to be submitted before the committee holds a vote on the nominee, not before the committee holds a hearing on the nominee,” she told the NewsHour.

The committee sent the NewsHour examples from the past, including George W. Bush education nominee Rod Paige whose hearing was on Jan. 10, 2001, but whose ethics paperwork was not complete until Jan. 18 of that year.

As the Senate Republicans and the ethics office debate what is required at nominee hearings, the ethics office is also raising questions about the Trump transition process.

The problems, the ethics chief wrote, have been the hearing schedule combined with a lack of timely information from nominees and the Trump team. “It has left some of the nominees with potentially unknown or unresolved ethics issues shortly before their scheduled hearings.” He did not indicate which nominees have completed which portions of the process.

The Office of Government Ethics, or OGE, is an independent agency whose current director was appointed by President Barack Obama. It was created after the Watergate scandal to oversee ethics for the executive branch.

Typically during the confirmation process, the ethics office writes reports outlining any possible ethics issues and steps the nominee agrees to take to resolve them.

But the ethics director implied his office has not had time to complete reviews yet because the Trump transition team did not “pre-clear” any potential nominees before announcing them publicly.

“In the past, the ethics work was fully completed prior to the announcement of nominees in the overwhelming majority of cases … and, therefore, there was no opportunity for undue influence on the independent ethics review process,” Shaub wrote.

The letter was also sent to Republican Senate Leader Mitch McConnell. His office told the PBS NewsHour that they have no comment at this time. The Trump transition team did not respond to questions and a request for comment.

The letter lands in a quickly-boiling political cauldron surrounding the Trump cabinet confirmation process. Senate Democrats have indicated they have sharp questions about, and may work to delay confirmation on, at least eight nominees. That has incensed Republicans, who point to 2009 when President Obama saw seven cabinet nominees confirmed on Inauguration Day and two more the next.

Republicans charge that Democrats are holding Trump’s choices to a different standard than Obama’s. They point to Democrats’ request for tax returns for several positions for which that step has not been required in the past. Republicans have rejected those requests and are not adding any new requirements for nominees.

But the disclosure from the Office of Government Ethics comes from an outside agency and indicates that at least some nominees have not yet met a significant and important requirement. Without ethics reports, senators would go into confirmation hearings without a usual source of potential questions.

Shaub called that a “cause for alarm” and said that he will not rush the ethics review process. “For as long as I remain director, OGE’s staff and agency ethics officials will not succumb to pressure to cut corners and ignore conflicts of interest,” he wrote.