House Democrats called for an emergency hearing Thursday following President Trump’s ouster of Attorney General Jeff Sessions. Democrats urged the passing of a bill that would protect special counsel Robert Mueller as he continues his probe into potential Russian collusion with the Trump campaign in the 2016 election. Democrats also formally requested the preservation of all documents related to Jeff Sessions’s firing, writing, “We remind you that concealing, removing or destroying such documents may constitute a crime.”

In the Senate, Republican Jeff Flake of Arizona and Democrat Chris Coons of Delaware said they will push for a floor vote on a bipartisan bill to protect Mueller’s probe.

Meanwhile, a New York Times op-ed published Thursday claims that Trump’s appointment of Matthew Whitaker as new acting attorney general is unconstitutional. The op-ed was written by Neal Katyal, the former acting solicitor general under President Obama, and George T. Conway, a high-profile litigator and husband to White House counselor Kellyanne Conway. They write, “Constitutionally, Matthew Whitaker is a nobody. His job as Mr. Sessions’ chief of staff did not require Senate confirmation. … For the president to install Mr. Whitaker as our chief law enforcement officer is to betray the entire structure of our charter document.”

This comes as Trump is reportedly considering former New Jersey Governor Chris Christie, Florida Attorney General Pam Bondi and Labor Secretary Alexander Acosta for attorney general.