The U.S. Senate is expected to vote Wednesday evening to approve Senator Jeff Sessions as the nation's new attorney general.
Republicans control the chamber and need only a simple majority in order to confirm President Donald Trump's appointee.
Sessions has faced sharp opposition from Democrats who question his record on immigration and civil rights, and who have suggested he is too close to Trump to put the rule of law ahead of politics.
Republicans however defend Sessions, saying his long Senate career has shown his integrity.
The confirmation vote has been delayed as Democrats use Senate rules to stretch out the time they have to speak on the floor about Sessions.
During his confirmation hearing before the Senate Judiciary Committee, Democrats invoked a little-used rule to delay a vote there by a day.
Republican lawmakers and Trump have complained that Democrats are unfairly delaying the confirmation process for the president's Cabinet. Democrats have countered that they need to fully examine the nominees, some of whom they say were slow to file information needed for ethics reviews.
The extended debate on Sessions that began Tuesday and stretched into Wednesday was highlighted by a rebuke of Democratic Senator Elizabeth Warren by Republicans.
She was reading a letter written by Coretta Scott King, the widow of assassinated civil rights icon Martin Luther King Jr. The letter was sent to the Senate Judiciary Committee in 1986 when Sessions was nominated for a federal judge seat.
Senate Majority Leader Mitch McConnell said Warren violated Senate rules by "impugning" Sessions, and she was barred from speaking further.
Warren responded by posting a Facebook video from outside the Senate floor that featured her reading the letter, which features King expressing "strong opposition" to having Sessions serve as a judge in Alabama. King said Sessions, then a federal prosecutor, worked against black citizens using their right to vote, and that "politically-motivated fraud prosecutions" and "indifference toward criminal violations of civil rights laws" showed he did not have the qualities to be a judge.
During his confirmation hearing, Sessions responded to allegations of racism by saying they were "damnably false."
The video had been viewed by 3.8 million people and shared 91,000 times in the first eight hours after it was posted.