The Department of Homeland Security on Wednesday said that David Pekoske, the head of the Transportation Security Administration, is the acting head of the department pending the confirmation of a permanent secretary.

Pekoske takes over the helm at DHS from Pete Gaynor, who was the acting Secretary of Homeland Security after Chad Wolf stepped down from the same position earlier this month. Gaynor, who had been the administrator of the Federal Emergency Management Agency, resigned.

President Biden had hoped the Senate would quickly confirm Alejandro Mayorkas, his nominee to lead DHS, but Sen. Josh Hawley (R-Mo.) on Tuesday placed a hold on the nomination. Instead of going straight to the Senate for a vote on Wednesday as Democrats had hoped for, the hold means Senate Homeland Security and Governmental Affairs Committee will mark up the nomination first. Mayorkas on Tuesday testified before the panel as part of the confirmation process.

A vote by the committee on Mayorkas could happen this week but could also be delayed until next week. Until Senate leaders agree on rules for organizing in the new Congress, the Republicans still control the committees.

Sen. Gary Peters (D-Mich.), currently the ranking member on the Senate Homeland Security and Governmental Affairs Committee and soon to be the panel’s chairman once Senate leaders agree on the new organization, is working with Sens. Ron Johnson (R-Wis.), the current chairman, and Rob Portman (R-Ohio), who will become the ranking member, to move forward with the markup.

Hawley said that Biden’s proposed immigration plan that includes “amnesty” for 11 million immigrants currently in the U.S illegally “comes at a time when millions of American citizens remain out of work and a new migrant caravan has been attempting to reach the United States. Mr. Mayorkas has not adequately explained how he will enforce federal law and secure the southern border given President-elect Biden’s promise to roll back major enforcement and security measures. Just today, he declined to say he would enforce the laws Congress has already passed to secure the border wall system. Given this, I cannot consent to skip the standard vetting process and fast-track this nomination when so many questions remain unanswered.

The Biden administration has directed a freeze on ongoing construction of physical barriers along portions of the southern border. Mayorkas told the Senate panel on Tuesday that he will execute on Biden’s directive. The administration also said it plans to emphasize spending on border security technology but hasn’t released specifics.

Pekoske became TSA Administrator in August 2017 for a five-year term. From April 2019 until November 2019, he also served as acting Deputy DHS Secretary under then acting Secretary Kevin McAleenan.

While Pekoske leads DHS, TSA’s acting chief is Darby Lajoye, who is the executive assistant administrator for Security Operations at the Agency. Stacey Fitzmaurice, the executive assistant administrator for Operations Support at TSA, is acting as the agency’s deputy administrator.