(CNN) President Donald Trump's interim pick to head the Justice Department has been on the job for four weeks, but Matthew Whitaker has been noticeably silent about how he is handling any potential conflicts of interest while guiding the department through one of the most politically charged environments in decades.

For now, officials in Deputy Attorney General Rod Rosenstein's office continue to handle management of special counsel Robert Mueller's investigation into Russian interference in the 2016 election, but Whitaker's ability to pull rank as the acting attorney general and overrule Rosenstein's judgment may prove crucial in coming weeks as the investigation winds down -- leading to mounting questions about what steps Whitaker has taken, or not taken, to heed any ethics advice after now serving 28 days as the nation's top law enforcement officer.

Democrats on the Senate Judiciary Committee renewed their concerns Tuesday, writing in a letter to Justice officials that Whitaker's financial disclosure forms were only recently certified as true by ethics officials (after multiple revisions), and moreover "the Department has not produced prior versions of Mr. Whitaker's financial disclosures, any ethics agreements he entered into with the Department, or any other ethics-related counseling he has received."

Also on Tuesday, hundreds of former Justice Department officials signed on to an open letter voicing their unease about his appointment and noting he "has not been fully vetted for any potential conflicts of interest."

Questions began soon after Whitaker's appointment last month, as his past skepticism of Mueller's work resurfaced, along with his personal tie to one of the witnesses in the probe -- all of which prompted calls for him to step aside from direct oversight of the investigation. The Justice Department, in turn, issued a broad statement suggesting that Whitaker would consult with ethics officials as he deemed necessary, but the department stopped short of confirming that he had, in fact, begun seeking ethics guidance on any possible conflicts.

"Acting AG Whitaker is fully committed to following all appropriate processes and procedures at the Department of Justice, including consulting with senior ethics officials on his oversight responsibilities and matters that may warrant recusal," Justice Department spokesperson Kerri Kupec told CNN on November 12.

It is not uncommon for the Justice Department to decline to discuss recusal issues when doing so may confirm the existence of certain investigations that are not yet public, but its steadfast refusal to confirm whether Whitaker has even initiated an ethics review has raised eyebrows.

"The whole point of the ethics rules is to ensure that government officials are working in the public interest free from conflicts. With every passing day, DOJ's silence undermines public confidence in the rule of law," Austin Evers, executive director of the watchdog organization American Oversight, told CNN. "The ethics analysis for Matthew Whitaker should be straightforward and it should be done by now."

While calls for information have been met with radio silence at the department thus far, Whitaker's private conversations with lawmakers have confirmed he has no intention of stepping aside.

After meeting with Whitaker on Capitol Hill just before Thanksgiving, Republican Sen. Lindsey Graham of South Carolina told reporters that Whitaker "believed he did not have a reason to recuse himself legally or factually."

Under Justice Department regulations , an employee must not participate in a criminal investigation if he has "a personal or political relationship" with any person or organization that is "substantially involved in the conduct that is the subject of the investigation" or could be "directly affected" by its outcome.

that Whitaker's predecessor, Jeff Sessions, recused himself in March 2017 from any investigation related to Trump's 2016 presidential campaign. White House officials, however, believehat Whitaker's situation differs from his former boss', because Sessions was a Trump campaign surrogate, whereas Whitaker's past interviews and writings on Mueller do not rise to the same level, in their view.

But in a few weeks, when Democrats take the reins in the House, Whitaker may face increasing pressure to answer these ethics-related questions.

Reps. Jerry Nadler of New York and Elijah Cummings of Maryland -- key Democrats slated to lead the House Judiciary and Oversight committees, respectively -- spoke to Whitaker by phone late last week, and while sources briefed on the call said the acting attorney general provided little information, one Democratic aide said the House Judiciary Committee expects him to answer questions fully in January.