Joe Biden has earned the endorsement of South Carolina congressman Jim Clyburn, bolstering the fomer vice president's prospects just days before the state's Democratic primary voters head to the polls.

Mr Clyburn is the majority whip in the House of Representatives, the state's most influential Democrat and the highest-ranking black member of Congress.

His support could prove invaluable for Mr Biden, who has faced middling support in the Democratic primary race so-far and is hoping for a strong performance in South Carolina, where he has counted on support from black voters. Mr Clyburn, according to South Carolina's Post and Courier has been known among some poltiical observers as South Carolina Deomcrats's "kingmaker".

"I know Joe, we know Joe, but most importantly Joe knows us," Mr Clyburn told reporters in North Charleston on Wednesday, with Mr Biden and other top supporters nearby.

Mr Clyburn also noted in an emotional moment that his late wife, Emily, who died just months ago, loved Mr Biden more than any other political leader and spoke highly of him and often.

Trump South Carolina rally Show all 5 1 /5 Trump South Carolina rally Trump South Carolina rally President Donald Trump, in town to support Gov. Henry McMaster, speaks to the crowd at Airport High School, Monday, June 25, 2018, in West Columbia, S.C. (AP Photo/Richard Shiro) Richard Shiro AP Trump South Carolina rally President Donald Trump gestures during a rally at Airport High School in West Columbia, S.C., Monday, June 25, 2018, for Republican Gov. Henry McMaster. (AP Photo/Susan Walsh) Susan Walsh AP Trump South Carolina rally President Donald Trump speaks during a rally at Airport High School in West Columbia, S.C., Monday, June 25, 2018, for Republican Gov. Henry McMaster. (AP Photo/Susan Walsh) Susan Walsh AP Trump South Carolina rally WEST COLUMBIA, SC - JUNE 25: President Donald Trump speaks during a campaign rally for South Carolina Governor Henry McMaster at Airport High School on June 25, 2018 in West Columbia, South Carolina. (Photo by Sean Rayford/Getty Images) Sean Rayford Getty Images Trump South Carolina rally WEST COLUMBIA, SC - JUNE 25: President Donald Trump speaks to the crowd during a campaign rally for South Carolina Governor Henry McMaster at Airport High School June 25, 2018 in West Columbia, South Carolina. (Photo by Sean Rayford/Getty Images) Sean Rayford Getty Images

When it comes to Donald Trump, Mr Clyburn said he has never been more fearful for the US, and said Mr Biden is the Democrat who can "restore the countrys dignity and respect".

South Carolina is largely viewed a make or break moment for Mr Biden, and what is likely his final run for the presidency.

After relatively meek showings in the first three states to vote — Nevada, New Hampshire and Iowa — he is relying on black voters in the state to throw their support behind him. A strong first-place showing in the state could solidfy him as the moderate Democrats' alternative to Bernie Sanders, who is leading the race nationally.

Over the past year, in part due to his strong ties to the state, Mr Biden has led in polls there, even as Mr Sanders and Tom Steyer have closed that gap in recent months. Mr Steyer, in particular, has been seen to be pulling African American voter support from Mr Biden in the state.