Senate Majority Leader Mitch McConnell told reporters that President Trump would probably to veto a joint resolution to terminate his declaration of a national emergency at the border, and he predicted a two-thirds majority of Congress was unlikely to overrule the veto.
Mr. Trump wants to use the declaration to unilaterally fund border security measures, including a wall at the southern border.
McConnell predicted that while the resolution would "in all likelihood" pass Congress, it would then get a veto that will "almost certainly be sustained," echoing assertions he made to reporters in his home state of Kentucky on Monday.
"I think what is clear in the Senate is that there will be enough votes to pass the resolution of disapproval, which will then be vetoed by the president, and then in all likelihood the veto will be upheld in the House," McConnell said in the Capitol on Monday.
Senate Minority Leader Chuck Schumer urged Republicans to vote to overrule a potential veto and stop the declaration of a national emergency.
"No president — none — should be allowed to discard the Constitution on a whim and do an end-run around a coequal branch of government," Schumer said.
Last month, Mr. Trump declared a national emergency to free up funds to build a wall between the U.S. and Mexico, citing a "humanitarian crisis" at the border. This declaration came after a 35-day partial government shutdown and three weeks of congressional negotiations, during which congressional Democrats refused to provide funds for the wall.
Democrats quickly proposed a resolution to stop the national emergency. In order to cancel a national emergency, Congress must approve a joint resolution disapproving it. There are enough Republicans in the Senate who have expressed opposition to the national emergency, ensuring that the resolution will pass both houses of Congress.
A two-thirds majority of Congress is needed to overrule a veto. It is unlikely that enough Republicans in either the House or the Senate would vote to override Mr. Trump's veto.