The deputy administrator of the Federal Railroad Administration is stepping down "effective immediately," the Transportation Department declared Saturday, further casting leadership of the agency in doubt as Senate Democrats have placed a hold on President Trump's nominee to fill the role.

The exit of Heath Hall, who had been acting FRA administrator, comes after it was revealed that while he worked at the top federal railroad safety regulator, he also appeared in media reports as spokesman for a sheriff's department in Mississippi.

Hall has a public relations and political consulting firm in Madison County and Politico reported that it continued to receive payments from the county from July 2017, one month after Hall took over as acting administrator, to December. The report said Hall had committed to keeping those services "dormant" during his tenure at the Transportation Department in a federal ethics form.

“DOT was unaware of the information that is being reported regarding outside work Heath Hall took on during his time at FRA, but those allegations, if true, are troubling," a DOT spokesperson said in a statement sent to the Washington Examiner. "Mr. Hall has resigned his position at the Department effective immediately."

The DOT's webpage for administrator is currently blank. DOT says Hall was not the acting administrator when he resigned.

Since last fall, Democrats, led by Senate Majority Leader Chuck Schumer, D-N.Y., have stalled the nomination of railroad executive Ronald Batory with a procedural hold to protest the Trump administration's rejection of a deal to help fund a multi-billion dollar infrastructure project, known as the Gateway Program, which would connect lower Manhattan and New Jersey with a rail tunnel underneath the Hudson River.

After a train carrying Republican lawmakers to a retreat crashed into a truck in Virginia late last month, killing one and injuring others, Transportation Deputy Secretary Jeffrey Rosen complained that the Democrats' refusal to allow the nomination of Batory to proceed posed a danger to the public.

“While the circumstances of that crash are being reviewed by the Federal Railroad Administration, it is clear that the agency needs to have its chief rail safety official in place,” Rosen said in a letter to Schumer.

“Today's tragic accident is not the first one to occur during the lengthy delay,” Rosen added in the letter obtained by NBC News. “In the interest of public safety, I am asking that you set aside wholly unrelated issues and remove your hold on his nomination to become the Federal Railroad Administrator."

The Commerce Committee had approved of Batory's nomination in a unanimous vote last summer. According to Politico, Hall had already recently taken a leave of absence due to a family emergency.

FRA's chief counsel, Juan Reyes, will remain as acting deputy administrator, DOT said.

Editor's note: This story has been updated with a statement from DOT.