WASHINGTON, DC - SEPTEMBER 16: Senate Armed Services Committee member Sen. Ted Cruz (R-TX) questions witnesses during a hearing about the Islamic State of Iraq and the Levant in the Hart Senate Office Building on Capitol Hill September 16, 2014 in Washington, DC. Senators questioned the top military and civilian leaders about the threat posed by the terrorist group calling itself ISIL. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON -- Sens. Ted Cruz (R-Texas) and Mike Lee (R-Utah) are calling on President Barack Obama's nominee for attorney general to weigh in on the constitutionality of the administration's plans to unilaterally grant deportation relief to undocumented immigrants.

"The Attorney General is the President's chief law enforcement officer. As such, the nominee must demonstrate full and complete commitment to the law. Loretta Lynch deserves the opportunity to demonstrate those qualities, beginning with a statement whether or not she believes the President’s executive amnesty plans are constitutional and legal," the conservative duo said in a statement Saturday.

On Saturday, Obama formally nominated Lynch, the U.S. attorney for Eastern New York, to replace Attorney General Eric Holder. If confirmed, she would be the first black woman to lead the department. Speaking at the White House, the president urged the Senate to confirm her, noting that it was "pretty hard to be more qualified for this job than Loretta."

Cruz and Lee also called for a vote on the nomination only after the new Congress convenes in January, echoing earlier calls from the incoming Senate Majority Leader, Mitch McConnell (R-Ky.). Though Obama said on Saturday that Lynch should be confirmed "without delay," sources told The Associated Press that the president has decided not to push Lynch's confirmation while Democrats retain control of the Senate and will instead wait until January.

However, the president has not shown signs of backing down from his earlier pledge to take executive action on immigration, despite his party's heavy losses in Tuesday's midterm elections.

"Before the end of the year, we're going to take whatever lawful actions that I can take," Obama said at a Wednesday press conference.

Cruz and several other conservative senators sent a letter to Senate Majority Leader Harry Reid (D-Nev.) this week threatening to use procedural means to block any potential executive action on the matter. But the issue could complicate Lynch's path to confirmation regardless of whether or not the president does proceed before January.