(CNN) Update April 21: The Florida lawmaker under fire over racially inflammatory remarks toward his African-American colleagues has resigned, a spokeswoman for the Florida Senate Majority Office told CNN. The embattled state senator, Frank Artiles, submitted his letter of resignation to Senate President Joe Negron on Friday, just days after apologizing on the Senate floor for his remarks.

Original story from April 20:

A Florida state senator is facing mounting pressure to resign after unleashing a tirade during a private conversation with African-American colleagues.

Troubles for Republican Sen. Frank Artiles began after reports surfaced he had used the N-word and cursed at a fellow senator.

Artiles was having drinks at the Governors Club in Tallahassee with fellow Sens. Audrey Gibson and Perry Thurston when he told the pair that Senate President Joe Negron had only risen to his position of power because "six [N-word]" in the Republican caucus elected him, The Miami Herald reported . Gibson and Thurston are both black.

Thurston confirmed the exchange to CNN.

On Wednesday, Artiles apologized on the Senate floor for his remarks.

"I extend a heartfelt apology to my colleagues and to all those I have offended," Artiles said in his prepared remarks.

He also apologized to Gibson for calling her a "bitch" during his tirade.

But the contrition may be too little, too late for the embattled lawmaker.

The Florida Democratic Party is demanding his immediate resignation: "His use of horrific racist and sexist slurs towards his colleagues is disgusting, unacceptable and has no place in our democracy or our society."

Negron called Artiles' remarks appalling.

"Racial slurs and profane, sexist insults have no place in conversation between Senators and will not be tolerated while I am serving as Senate President."