The U.S. Senate is due to begin voting late on Tuesday on President Donald Trump's request to slash billions in spending on foreign aid and public broadcasting previously approved by Congress, the latest test of Trump's control over his fellow Republicans.

Senate GOP leaders are looking to avoid a repeat of the lengthy and sometimes bewildering floor process that led to the passage of the Trump tax bill by locking down key details with holdouts before the chamber moves to a vote-a-rama Wednesday on a bill to claw back funding.