NEW YORK — Stevie Wonder, whose advocacy helped make the Rev. Martin Luther King Jr.’s birthday a national holiday, is urging the incoming Biden administration to form a national commission on equality.

Wonder released a video message Monday in the form of an open letter to King, who was assassinated in 1968 and whose birthday was made a federal holiday late in 1983. Wonder met King when he was a teenager and later wrote the tribute song “Happy Birthday,” which urged that the government formally establish a Martin Luther King Jr. Day.

King was born Jan. 15, 1929, and his birthday celebrated on the third Monday in January.

“For 36 years, we’ve had a national holiday honoring your birthday and principles, and you would not believe the lack of progress. It makes me physically sick,” Wonder said in his message.

“It is time for all to take the only stand. We can not be afraid to confront a lie and a liar. Those in leadership who won’t or don’t acknowledge the truth should be held accountable. Dr. King, these times require courage, as they did when you lived and paid the ultimate price.”