And by doing so, majority Republicans just handed the liberal firebrand a megaphone -- further elevating President Donald Trump's fiercest and most prominent critic in the Senate and turning her into a Democratic hero.

The rebuke of Warren came after the Massachusetts Democrat read a letter written 30 years ago by Coretta Scott King , the widow of Martin Luther King Jr., opposing the nomination of Jeff Sessions for a federal judgeship.

Warren cited the letter during a debate on the nomination of Sessions -- now an Alabama senator -- as Donald Trump's attorney general. Reading from King's letter to members of the Senate Judiciary Committee in 1986, Warren said: "Mr. Sessions has used the awesome power of his office to chill the free exercise of the vote by black citizens in the district he now seeks to serve as a federal judge."

Republicans cried foul -- charging that Warren violated Senate rules against impugning another senator. A vote along party lines upheld that decision, turning what could have been an ordinary late-night partisan floor speech for political devotees into a national story.

"They can shut me up, but they can't change the truth," Warren later told CNN's Don Lemon.

The moment immediately galvanized the Democratic base. Weeks after the women's marches around the country turned out droves of anti-Trump protesters, Warren -- silenced by male senators for attempting to read a letter from a civil rights icon -- had given those women a new rallying point.

Adding fuel to the backlash, supporters noted the apparent hypocrisy that Warren's male colleagues were able to read from the letter uninterrupted. Sen. Tom Udall of New Mexico read the letter to enter it into the congressional record Wednesday morning and Sen. Jeff Merkley was allowed to read from King's letter Tuesday night, though he couched his remarks as only reading portions of the letter and with the context to be in line with Senate rules.

Warren is now forbidden from participating in the floor debate over Sessions' nomination ahead of a confirmation vote expected Wednesday.

"I literally can't be recognized on the floor of the Senate," she told Lemon. "I have become a nonperson during the discussion of Jeff Sessions."

Senate Majority Leader Mitch McConnell defended invoking Rule 19, a rarely used chamber regulation that prohibits senators from impugning each other.

"She was warned. She was given an explanation. Nevertheless, she persisted," the Kentucky Republican said on the Senate floor, delivering an instantly classic line -- the kind liberals imagine being replayed ad nauseum in TV ads in a future presidential campaign.

It couldn't have come at a better time for Warren, who is up for re-election in 2018. On Tuesday, she announced she hired an aide who is an expert on national security, a move that could help burnish her expertise in that area, as well as the publication of a new book, which will become available in April.

Liberals had been frustrated with Warren's vote in committee in favor of Ben Carson, Trump's nominee for secretary of Housing and Urban Development.

No more.

By Tuesday night, the hashtag #LetLizSpeak was trending on Twitter. Millions of people had also watched on Facebook as Warren read the letter outside the Senate chamber.

MoveOn members contributed $250,000 to Warren's re-election campaign in about 12 hours.

Warren used Twitter to attack Sessions and McConnell.

"I will not be silent about a nominee for AG who has made derogatory & racist comments that have no place in our justice system," she wrote.

In a follow-up tweet, she said: "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."

And then: "Tonight @SenateMajLdr silenced Mrs King's voice on the Sen floor - & millions who are afraid & appalled by what's happening in our country."

I will not be silent about a nominee for AG who has made derogatory & racist comments that have no place in our justice system. — Elizabeth Warren (@SenWarren) February 8, 2017

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

Tonight @SenateMajLdr silenced Mrs King's voice on the Sen floor - & millions who are afraid & appalled by what's happening in our country. — Elizabeth Warren (@SenWarren) February 8, 2017

Warren went straight from the Senate floor to a call-in appearance on Rachel Maddow's MSNBC show, a favorite of progressives. "I've been red-carded on Sen. Sessions. I'm out of the game of the Senate floor," she told Maddow.

She also read King's letter outside the Senate floor in a Facebook live video.

Meanwhile, the Democratic National Committee blasted out a supportive statement. Interim chairwoman Donna Brazile said: "It's a sad day in America when the words of Martin Luther King Jr.'s widow are not allowed on the floor of the United States Senate. Let Elizabeth Warren speak."

The moment became a rallying cry for fellow Democrats. California Sen. Kamala Harris took to the Senate floor to call the vote to silence Warren "outrageous."

"I never ever saw a time when a member of the Senate asked to put into the record a letter -- especially by a civil rights icon -- and somebody objected," said Sen. Patrick Leahy, D-Vermont.

The Senate descended into a series of complaints about declining decorum on both sides.

"We have to treat each other with respect or this place is going to devolve into a jungle," said seven-term Utah Republican Sen. Orrin Hatch.

JUST WATCHED Sen. Warren: Overturn Trump's executive order Replay More Videos ... MUST WATCH Sen. Warren: Overturn Trump's executive order 00:56

Then Democrats brought out examples of Republicans who had crossed similar lines and not been shut up the way Warren was forbidden from participating.

Senate Minority Leader Chuck Schumer's office highlighted Texas Sen. Ted Cruz's accusation that McConnell had told a "flat-out lie" about the future of the Export-Import Bank in 2015.

Warren sat on the Senate floor, though, silently. She had already had her moment.

CORRECTION: An earlier version of this story misidentified the senator from New Mexico. It is Tom Udall.