President Trump threw Capitol Hill into fresh chaos before 4am Wednesday, threatening to block his own intelligence chief's confirmation hearing unless the Senate approves his controversial pick for a separate top law enforcement job.

In a pre-dawn Truth Social post, Trump announced he was cancelling the confirmation hearing for Jay Clayton, his nominee for Director of National Intelligence, and would keep acting DNI Bill Pulte in post until the Senate confirms Jamie McDonald as US Attorney.

'We are canceling the Senate Hearing RE: DNI today, and will not be going forward until Jamie McDonald is approved to be U.S. Attorney,' Trump wrote. 'In the meantime, Bill Pulte will remain as the Acting Director of National Intelligence.'

The move puts Republican senators in an uncomfortable position. Clayton, a former SEC Chair and current US Attorney for the Southern District of New York, had been sailing toward easy bipartisan confirmation - with both parties eager to remove Pulte, who has no intelligence background, from the top spy job.

The urgency is real: FISA, the Foreign Intelligence Surveillance Act, is set to expire, and lawmakers on both sides want a confirmed, credentialled DNI in place before it does.

Clayton was nominated after Trump's original DNI pick - Pulte, head of the Federal Housing Finance Agency - drew swift blowback for his lack of intelligence experience. 

The vacancy arose when Tulsi Gabbard left the role to support her husband Abraham through cancer treatment.

Arkansas Senator Tom Cotton, chairman of the Senate Intelligence Committee, had intended to press ahead with Clayton's hearing Wednesday morning unless Trump directly ordered otherwise.

Trump has compounded Republican headaches further by demanding FISA reauthorisation be bundled with the SAVE America Act - his voter-integrity bill requiring Americans to show a passport, birth certificate or citizenship-designated REAL ID before voting. Student IDs and utility bills would not qualify.

Senate Majority Leader John Thune told reporters Monday the demand was 'unrealistic.' 

 The bill requires a 60-vote supermajority - a far steeper bar than the simple majority it cleared in a procedural test vote in March.

House Republicans are pushing back. 'The House has already passed both the SAVE America Act and FISA reauthorization with reforms,' Representative Warren Davidson told the Daily Mail. 'The Senate needs to stop holding this up and do its job.'