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Democrats rallied around Elizabeth Warren on Wednesday after the Massachusetts senator was silenced for reading from a 30-year-old letter written by the Rev. Martin Luther King Jr.'s widow criticizing attorney general nominee Jeff Sessions.

Senate Republicans voted to rebuke Warren after she read from a letter that Coretta Scott King wrote criticizing Sessions, a Republican senator from Alabama, who was confirmed Wednesday night as attorney general. The 1986 letter, written when Sessions — then the U.S. attorney for the Southern District of Alabama — was being considered for a federal judgeship.

Related: Jeff Sessions Confirmed as Attorney General After Nasty Battle

It said Sessions used the "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."

Democrats this week have spoken out forcefully against President Donald Trump's Cabinet nominees, even though they lack the votes to derail even the most contentious picks.

Education Secretary Betsy DeVos needed Vice President Mike Pence to cast a tie-breaking vote in her favor on Tuesday, marking the first time a vice president's ballot was needed to confirm a Cabinet nominee.

"Democrats have the minority in the House, the minority in the Senate, but that does not make us the minority party," Warren said Wednesday in an interview on MSNBC. "We are the party of opposition, and that is our job. But our tools are very limited."

The rare move to silence a senator for impugning a colleague sparked a #LetLizSpeak social media campaign Tuesday night and prompted a number of Democrats to defend Warren, a liberal firebrand who's the subject of heavy speculation about a 2020 presidential bid.

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Democratic Sens. Tom Udall of New Mexico and Sherrod Brown of Ohio and Indepedent Sen. Bernie Sanders of Vermont all took to the floor reading King's letter Wednesday morning without Republican objection.

Aides to the Republican leadership said Warren wasn't punished for simply reading the letter, but for ignoring warnings about being silenced and delivering a disparaging speech that went beyond King's words.

Sen. Udall reads letter from Coretta Scott King on Senate floor that Sen. Warren was stopped from reading last night https://t.co/G7juuw3be2 — NBC News (@NBCNews) February 8, 2017

Sanders called it "unconscionable and outrageous" that Warren was cut from the debate, and he called on Senate Majority Leader Mitch McConnell, R-Kentucky, to apologize.

The marathon debate on the confirmation of Sessions, which stretched overnight into Wednesday afternoon, came to a temporary halt Tuesday night when McConnell objected to a speech that Warren was giving.

McConnell and other Republicans said Warren violated Senate rule No. 19, which says senators can't "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."

Related: Dems Pull Second All-Nighter at Senate to Oppose Trump Nominee

The Senate voted along partisan lines, 49-43, to admonish Warren, effectively barring her from speaking during the remaining debate on Sessions.

"She has been warned multiple times (not just today)," McConnell spokesman Don Stewart told NBC News by email. "And after additional warning today, she was found in violation of the rule. She appealed the ruling and lost."

Democrats stood to defend Warren, a darling of the left, leading to #LetLizSpeak hashtag.

Senate GOP has now ruled that any Democrat who criticizes Sessions' record will be stripped of right to speak. It's outrageous. #LetLizSpeak pic.twitter.com/Q6NaskHOAh — Jim McGovern (@RepMcGovern) February 8, 2017

"I've been red-carded on Senator Sessions. I'm out of the game on Senator Sessions," Warren said Tuesday night on MSNBC's "The Rachel Maddow Show."

Abandoning the sports analogies, Warren then urged all Americans to read Scott's letter for themselves.

"It is eloquent, and it reminds us of a time in history that we would like to think is far behind us but reminds us that it is not," she said.

Warren also took to Twitter, saying McConnell was, in reality, silencing King.

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

Sen. Kamala Harris, D-California, meanwhile, posted the full letter and excerpts after Warren was sanctioned.

… to our courts. Mr. Sessions has used the awesome power of his office in a shabby attempt to intimidate and frighten elderly black voters … — Kamala Harris (@KamalaHarris) February 8, 2017

Senate Democratic leader Chuck Schumer of New York objected to the ruling, calling it "selective enforcement" and citing previous apparent violations by Republicans that went unpunished.

At times in the past, Schumer said in a statement released by his office, Republican senators had accused their colleagues of telling "a flat-out lie," of "stirring up global hysteria to score political points" and of engaging in "bitter, vulgar, incoherent ramblings."

That last one came from Sen. Tom Cotton, R-Arkansas, who last May denounced Schumer's predecessor, former Minority Leader Harry Reid, D-Nevada, for what he called "cancerous leadership" designed to "protect his own sad, sorry legacy."

But Sen. Orrin Hatch, R-Utah, insisted that Warren's actions had no place in the Senate.

"Even if what she said was true, it wasn't the right thing to do," Hatch said. "I've been appalled at the way Democrats have treated Jeff Sessions."