Minority Leader Mitch McConnell (R-KY) made the shocking decision to recommend Republicans block the advancement of the Senate pro-migration border bill.

That first procedural vote was set for Wednesday. It is unknown if Majority Leader Chuck Schumer (D-NY) will forge ahead, although that is likely.

McConnell cited the overwhelming number of Senate Republicans planning to vote against the measure either on substance or because they wanted more time, according to Punchbowl News.

The longtime Republican leader has spoken in favor of the deal and did not express any personal hesitations about the legislation to his colleagues.

According to Punchbowl, McConnell said the political mood in the country has changed since negotiations began months ago. At that time, McConnell and Democrat leaders agreed to pair foreign aid to Ukraine, of which McConnell is the Senate’s greatest champion, with a border compromise.

Migrants walk beside the US-Mexico border fence in Lukeville, Arizona, on Dec. 11, 2023. (Eric Thayer/Bloomberg News via Getty Images)

Democrats, although also generally in favor of aiding Ukraine’s stalemated war against Russia, used McConnell’s fervor for Ukraine aid against Republicans, dangling a proposed border compromise in exchange for aiding the European nation.

Majority Leader Chuck Schumer (D-NY) touted his close work with McConnell on the deal. “I have never worked more closely with Leader McConnell on any piece of legislation as we did on this,” Schumer told reporters on Sunday.

Leaked details of the secretive deal, which McConnell’s chosen Republican lead negotiator Sen. James Lankford (R-OK) and other allies denied, were confirmed Sunday upon the bill’s release. The overwhelming opposition led to McConnell altering his plan Monday night.

Even Lankford, who continued championing the deal leading up to Monday night’s Senate Republican Conference meeting, would not say after the meeting if he would vote to move forward Wednesday on the deal he negotiated, according to the Huffington Post.

The plan would set into law many of the open border pro-migration policies Biden has instituted that have led to a wave of migration that has overwhelmed law enforcement at the southern border.

This is a developing story.

Bradley Jaye is a Capitol Hill Correspondent for Breitbart News. Follow him on X/Twitter at @BradleyAJaye.