What happens next as Joe Biden seeks to pass baton to Kamala Harris?

Democrats face unprecedented challenges as Joe Biden steps aside, endorsing Kamala Harris, leading to a murky convention process.

With U.S. President Joe Biden ending his reelection bid and endorsing Vice President Kamala Harris, Democrats now must navigate a shift that is unprecedented this late in an election year.

Democrats are set to hold their convention in Chicago on August 19-22. What was supposed to be a coronation for Mr. Biden now becomes an open contest in which nearly 4,700 delegates will be responsible for picking a new standard-bearer to challenge Republican Donald Trump in the fall.

The path ahead is neither easy nor obvious, even with Mr. Biden endorsing Harris. There are unanswered questions about logistics, money and political fallout.

Mr. Biden won every State primary and caucus earlier this year and only lost the territory of American Samoa. At least 3,896 delegates had been pledged to support him.

Current party rules do not permit Mr. Biden to pass them to another candidate. Politically, though, his endorsement is likely to be influential.

With Biden stepping aside, Democrats technically start with an open convention. But realistically, his endorsement pushes Democrats into murky territory.

The immediate burden is on Ms. Harris to solidify support across almost 4,000 delegates from the states, territories and District of Columbia, plus more than 700 so-called super-delegates that include party leaders, certain elected officials and former presidents and vice presidents.