South Carolina Rep. Jim Clyburn will endorse Hillary Clinton for president Friday, campaign sources confirm to Fox News.

Clyburn is expected to announce the endorsement during a press conference at Allen University in Columbia, S.C. His backing should provide Clinton with a boost in a state where black voters are likely to make up a majority of the Democratic primary electorate.

In a newly released Fox News Poll, South Carolina Democratic primary voters favor Clinton over Bernie Sanders by 28 points.

Clyburn, who remained neutral during the 2008 election, told the Washington Post Tuesday that his initial plan was to avoid endorsing a Democratic candidate during this election.

“That was certainly my intention,” he told the paper about staying neutral. “But I am re-evaluating that. I really am having serious conversations with my family members.”

Clyburn is one of the top African-American leaders on Capitol Hill and the highest ranking elected Democrat in the state.

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The South Carolina Democratic primary is February 27.

The Associate Press contribute to this report.