Sen. Bernie Sanders on Monday endorsed his longtime rival former Vice President Joe Biden, a move aimed at unifying a Democratic Party long fractured along moderate and liberal lines ahead of the election match-up against President Donald Trump.

Sanders cited the novel coronavirus outbreak as a reason for the party to come together behind Biden, the likely Democratic presidential nominee after the progressive firebrand Sanders suspended his White House campaign.

Sanders¡¯ endorsement during an online campaign event came as Biden¡¯s team had already begun reaching out to advocacy groups on the left to enlist their support for the Nov. 3 general election battle against the Republican Trump.