Washington DC - President Donald Trump on Sunday threatened not to sign any other legislation into law until his bill mandating severe voting rights restrictions has been successfully passed.

"Great Job by hard working Scott Pressler on Fox & Friends talking about using the Filibuster, or Talking Filibuster, in order to pass THE SAVE AMERICA ACT, an 88% issue with ALL VOTERS," Trump rambled in a Sunday post on Truth Social.

"It must be done immediately. It supersedes everything else. MUST GO TO THE FRONT OF THE LINE. I, as President, will not sign other Bills until this is passed, AND NOT THE WATERED DOWN VERSION."

Trump's rant comes as his Safeguard American Voter Eligibility Act (SAVE America Act) waits to be voted on by the Senate after passing through the Republican-held House of Representatives in February.

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It will face an uphill battle in the upper chamber, however, as a supermajority of 60 votes will be needed for it to pass, which would require a significant – and unlikely – number of Democratic defections.

As a result, Trump and some of his Republican allies are calling for a weakening of the Senate's filibuster rules that would reduce the number of votes needed to pass legislation such as the SAVE America Act. The president has also threatened to bypass Congress completely.

The legislation forces voters to provide proof of citizenship when registering to vote and introduces a series of criminal penalties for officials who register someone without documentation.

Election experts have warned the bill would be a "nightmare" for voters, millions of who could be disenfranchised by its provisions.