Republican senators announced Friday that they plan to challenge President Obama’s recent controversial appointments in court.

Thirty-nine GOP senators have signed onto a letter announcing their intention to file a joint amicus brief in a court challenge against Obama’s recess appointments to the Consumer Financial Protection Bureau and the National Labor Relations Board last month.

{mosads}”We refuse to stand by as this President arrogantly casts aside our Constitution and defies the will of the American people under the election-year guise of defending them,” Sen. John Cornyn (R-Texas) said in a statement.

The White House has argued that the recess appointments were legal because the Senate’s pro forma sessions, in which a lone senator typically bangs the gavel once every three days, count as the chamber being in recess. Republican lawmakers disagree and say that the pro forma sessions do mean the Senate is in session and so no appointments could be made.

The court challenge with which the senators plan to file the brief has not been chosen yet.