Cruz: Trump "Unhinged", Trump: Cruz is a liar, Obama searches for Supreme Court judge

White House dismisses GOP 'bluster' on Scalia replacement

The White House is making clear that President Barack Obama will defy Republicans in Congress and on the campaign trail who want him to leave the momentous task of nominating a new Supreme Court justice to the next administration.

"This is not the first time that Republicans have come out with a lot of bluster, only to have reality ultimately sink in," White House Deputy Press Secretary Eric Schultz told reporters Monday.

Schultz pointed to previous White House victories over the GOP-led Congress -- raising the debt limit, implementing the Iran nuclear deal and reauthorizing the Export-Import Bank -- and said history shows "Republicans fell back when their positions aren't tenable."

Donald Trump: Ted Cruz is 'unstable'

Donald Trump escalated his battle with Ted Cruz on Monday, calling the Texas senator "unstable," threatening a lawsuit and urging the Republican National Committee to "intervene."

The billionaire businessman later held a press conference in which he said he "never ever met a person that lies more than Ted Cruz."

Trump continued to heap criticism on Cruz in an interview with CNN's Jim Sciutto Monday afternoon on "The Lead," saying that with "guys like Ted Cruz -- it's all talk and no action."

"He's a very bad guy. He's a very nasty guy. He's got no endorsements from any senators who he works with. He'll never be able to unify anything," Trump said of Cruz.