Senate Majority Leader Mitch McConnell, R-Ky., could soon play a key role in protecting President Trump's proposed border wall by refusing to hold a vote on a measure aimed at nullifying Trump's national emergency declaration.

Congress is poised to send Trump a resolution in the coming weeks that rescinds the national emergency Trump issued on Friday to justify shifting billions of dollars in federal funds for border wall construction.

If the House and Senate pass that resolution, Trump would likely veto it, after which the House and Senate could try to override that veto. But even if the Democratic-led House overrode Trump's veto, McConnell has the power to ignore that House vote and refuse to reconsider it at all.

“Nothing in the Constitution requires that either chamber vote directly on the question of repassing a vetoed bill,” the Congressional Research Service reported in 2015, referring to a vote to override a veto. “If either chamber fails to vote on the question, then the measure dies.”

Democrats who control the House majority are poised to easily approve a yet-to-be-introduced resolution to rescind the national emergency. The Senate would be forced to vote on the resolution, and a simple majority would require only a handful of Republicans to join Democrats to pass it.

Lawmakers predict if such a resolution were introduced, it would win enough Senate support to clear Congress and end up on Trump’s desk.

But Trump’s likely veto would send it back to the House, where a two-thirds majority would be required to override the veto. It's not clear the votes are there in the House, but even if they are, McConnell could shield Trump by ignoring the issue the second time around.

A McConnell spokesperson declined to speculate on how McConnell might act at any point in the process.

McConnell does not favor Trump’s use of a national emergency to move federal funds. He urged Congress to instead find a legislative compromise to provide enough funding to satisfy the president.

But the final spending and border deal Trump signed Friday included only $1.375 billion for building physical barriers along 55 miles of the southern border, far less than the $5.7 billion Trump was seeking.

McConnell announced Thursday he told President Trump he will back the national emergency declaration.

On Friday, McConnell blamed Democrats for refusing to legislate more border wall funding. He called Trump’s decision to announce emergency action “a predictable and understandable consequence of Democrats’ decision to put partisan obstruction ahead of the national interest.”