Warren had been attempting to read a 1986 letter from Coretta Scott King criticising Trump's nominee Jeff Sessions
Republican senators in the US last night voted to silence Democrat Elizabeth Warren as she protested against the nomination of Jeff Sessions for the job of US attorney general.
Senator Warren - one of the the most high-profile and progressive US politicians - was speaking on the Senate floor ahead of this week's confirmation vote for Senator Sessions.
She was attempting to read a letter from Coretta Scott King - Martin Luther King's wife - from 1986, which urged the then-Senate to vote against the ultimately unsuccessful nomination of Sessions as a federal judge.
The letter claims: "Mr Sessions has used the awesome powers of his office in a shabby attempt to intimidate and frighten elderly black voters. For this reprehensible conduct, he should not be rewarded with a federal judgeship."
Warren's attempt to read the letter drew an objection from Republican majority leader Mitch McConnell, citing a rule regarding senators criticising their colleagues.
The rarely invoked rule prohibits senators from “directly or indirectly, by any form of words impute to another Senator or to other Senators any conduct or motive unworthy or unbecoming a Senator”.
Senators ultimately voted by 49-43 to uphold the objection.
The decision to silence Warren provoked a furious debate on social media and in the Senate itself, with the hashtag '#LetLizSpeak' becoming a trending topic on Twitter.
Senator Cory Brooker suggested: "McConnell didn't just silence [Senator Warren] - he silenced civil rights icon Coretta Scott King."
I will not be silent while the Republicans rubber stamp an AG who will never stand up to the @POTUS when he breaks the law.— Elizabeth Warren (@SenWarren) February 8, 2017
Warren herself decided to read her full planned speech in a Facebook video. The video has already been viewed more than 3 million times.
The Senate - which has a Republican majority - is expected to confirm Sessions' nomination when it comes to a vote, which is likely to happen later today.
Yesterday, US Vice President Mike Pence was forced to break an historic tie-break vote to confirm Betsy DeVos as education secretary.
President Trump overnight took to Twitter to claim: "It is a disgrace that my full Cabinet is still not in place, the longest such delay in the history of our country. Obstruction by Democrats!"
Although the confirmation pace has been slightly slower for President Trump, US Senate records confirm Obama's first cabinet was not in place by this time in 2009. Secretary of Labor Hilda Solis was not confirmed until February 24th 2009.
However, several of Obama's nominations had withdrawn their names before the planned hearings - leading to delays until later in the year.