Donald Trump's iron grip on the Republican Party appears to be crumbling in real time.

A high-stakes White House summit with Speaker Mike Johnson and top GOP leaders was abruptly cancelled Thursday amid a deepening rift between the President and his own party over a $1.8 billion fund critics are openly denouncing as a 'slush fund.'

The meeting was meant to salvage the stalled $70 billion immigration enforcement bill the administration is counting on to fund its deportation operation through 2029. 

Instead, senators filed out of a tense closed-door session with acting Attorney General Todd Blanche and effectively pronounced the bill dead for the week. 

The vast majority of Senate Republicans, including normally reliable Trump loyalists like Senators Katie Britt and Tommy Tuberville, confronted Blanche with grave concerns that the fund could funnel taxpayer money to rioters who assaulted police officers on January 6, 2021.

Senate Majority Leader John Thune pulled the plug on the votes by sending lawmakers home until June 1.

Thune's public break is officially tied to the uproar over Trump's so-called 'slush fund' to reward political allies who claim the Biden Justice Department targeted them.

But privately, sources say the majority leader is seething over Trump's decision earlier this week to endorse Ken Paxton over Thune's close ally, John Cornyn, in the Texas Senate GOP primary.