Do high-profile endorsements boost Biden's chances?

What’s happening: In the span of three days, Joe Biden received endorsements from a trio of the Democratic Party’s most prominent voices, as his presidential campaign shifts from the primary to the upcoming general election against Donald Trump.

The first endorsement came from Sen. Bernie Sanders, Biden’s chief rival in the primary. Sanders called for the party to come together to defeat Trump, whom he called “the most dangerous president in the modern history of this country.” The duo also announced the creation of six “working groups” to help...