Story highlights Jackson ran for president in 1984 and 1988

He says Sanders should focus on unity

(CNN) Civil rights leader Jesse Jackson is urging Bernie Sanders, amid escalating tensions within the Democratic Party, to keep his eye on the ball: Defeating Donald Trump in November.

Jackson told CNN Thursday morning that he has been in touch with advisers to both Sanders and Hillary Clinton in recent days to emphasize the importance of party unity as Democrats prepare for a likely general election fight against Trump.

Sanders "must support the winner, Hillary, over Donald Trump. That's his very public position and I hope he will hold that position," Jackson said, adding that the Democratic primary should be viewed as the "intra-league competition" that precedes the battle for the White House in November.

The Clinton campaign declined to comment and the Sanders campaign did not immediately respond to a request for comment.

Despite calls from some party leaders for Sanders to drop out, Jackson said he believes the Vermont senator has "every right" to remain in the race until someone has reached the delegate threshold to clinch the party's nomination. However, once Clinton becomes the nominee, Sanders must work to ensure that his supporters don't assume that the only option come November is to "stay home or support Trump," Jackson added.

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