South Carolina Rep. Jim Clyburn, the number three Democrat in the House, has decided to endorse Hillary Clinton, CBS News confirms.

Clyburn will announce his endorsement, first reported by Buzzfeed, at an event at Allen University in Columbia, South Carolina Friday morning. The Clinton campaign is billing it in a press release this way: "Campaign to Announce Momentous SC Endorsement."

Clinton won't be present for the announcement because she'll be campaigning in Nevada, where Democrats will caucus Saturday.

The influential South Carolina representative had originally intended not to endorse, but said last week in an interview with the Washington Post that his family and friends were pressuring him to endorse. He did not make an endorsement in the 2008 Democratic race.

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Clyburn is the dean of the South Carolina congressional delegation and the first African American elected to Congress from the state since Reconstruction.

CBS News' Rebecca Shabad contributed to this report