Watch live: Senators to vote on Jeff Sessions for attorney general

Tensions over confirming President Donald Trump's cabinet nominees erupted late Tuesday in the US Senate, where a lawmaker's criticism of attorney general pick Jeff Sessions led to the very rare reprimand of a senator.

Senate Democrat Elizabeth Warren was told to sit down for reading a 1986 letter critical of Sessions written by Coretta Scott King, widow of slain civil rights leader Martin Luther King Jr.

The chamber's Republican leader Mitch McConnell interrupted Warren to accuse her of having "impugned" Sessions, a fellow senator.

"The senator has impugned the motives and conduct of our colleague from Alabama, as warned by the chair," McConnell said, taking the extraordinary step of invoking Senate Rule 19 that prohibits highly critical remarks against a fellow senator.

"The senator will take her seat," said the presiding officer, Senator Steven Daines. When Warren challenged the ruling, the Senate voted along party lines to uphold it.

It was a rare and powerful rebuke in the body where decorum is a cherished tradition. 

A confirmation vote for Sessions as attorney general is expected Wednesday evening around 6:50 pm EST. Watch the proceedings live here:

Tensions have soared in the few weeks since Trump took office, particularly over the process of confirming his cabinet nominees.

During debate over education secretary nominee Betsy DeVos, Democrats held the Senate floor Monday through the night as a protest against her nomination.

She was eventually confirmed Tuesday, but only when Vice President Mike Pence was brought in to break a 50-50 tie.

Pressure built during debate about Sessions, whose record on civil rights ultimately doomed his nomination to a federal judgeship in the 1980s.

At the time King wrote the Senate Judiciary Committee warning that Sessions used to "intimidate and chill" voters, and that confirming him as a judge would have "a devastating effect" on the US justice system.

"Mr. Sessions has used the awesome powers of his office in a shabby attempt to intimidate and frighten elderly black voters," she wrote.

Warren, a potential 2020 presidential candidate, was reading the King letter when she was blocked from continuing, a move that astonished Democratic Senator Sheldon Whitehouse.

With the ruling decided, "I don't know how we go about doing our duties," he said. "Are we supposed to simply blind ourselves to derogatory information?"

An exasperated Senator Orrin Hatch, the longest-serving Republican currently in the Senate, called for a more dignified debate of Trump's nominees. 

Senators must treat one another with respect, "or this place is going to devolve into nothing but a jungle," he said.