After years of frustration with his leadership, Mitch McConnell (R-KY) is facing a full-on mutiny over his cooperation on President Biden's so-called border bill.

Wisconsin senator Ron Johnson (R) accused the longtime conference leader of deceiving his Republican colleagues about the negotiations that led to the "monstrosity" of an immigration bill. 

Without telling Republicans, McConnell took border security "off the table," Johnson claimed in a live chat on X.

McConnell nailed...

Johnson lamented that the final text of the border bill fell far short of securing the border despite strong public support for immigration restrictions.

"We end up with this monstrosity of a bill - it's an immigration bill, it's not a border security bill," he said.

The border bill was shot down last week, with even McConnell voting against it after furious Republican backlash.

WATCH: Sen. Ron Johnson exposes how Mitch McConnell betrayed Republicans on border security. pic.twitter.com/ijWTzGauff

— The Post Millennial (@TPostMillennial) February 13, 2024

While some have chalked up McConnell's initial cooperation on the bill to a tactical blunder, some, like Johnson, see a more devious motive in play.

The border issue has been entangled with aid to Ukraine, a top priority of McConnell and like-minded Russia hawks.

Johnson said that McConnell's top concern during "secret" negotiations was unblocking support for Ukraine, not the southern border.

"When we entered this thing, McConnell, his top priority was funding for Ukraine. But public opinion and the very strong political rhetoric that we ought to secure our own border before we spend $60 billion to secure Ukraine's, was effective."

"McConnell just took that off the table - and that moment of leverage we had...has been lost," Johnson said.

McConnell wanes...

President Trump and other Republicans have furiously objected to supporting Ukraine without first securing the southern border with Mexico, which has been overrun with record numbers of illegal immigrants.

The issue has become a liability for Biden, who touted the border bill as tough and "bi-partisan" ahead of the November election.

But Republicans have blasted the bill as too weak and little more than a strategic move by Democrats to shift blame for the border crisis which they say Biden has the power to solve independently.

In the wake of the border bill's demise, McConnell has faced pressure to resign from Republican senators who say he has failed to prioritize a conservative agenda.

A fixture in Washington, McConnell has long enjoyed the deference and respect of his Republican colleagues, who stayed mostly quiet during a widely publicized health scare last year.

But the 81-year-old is seeing his influence wane as President Trump, a longtime foe of his, continues to dominate the political scene.

Senate Republicans have parroted Trump's foreign policy rhetoric as Congress continues to weigh foreign aid for Ukraine separately from the border.

22 Senate Republicans helped pass a nearly $100 billion package to Ukraine and Israel on Tuesday, but more Republicans were against it, including famous hawks like Lindsey Graham (R-SC).