Mr. Biden, 76, is set to offer himself as a moderate and a trustee of former President Barack Obama’s legacy, which he will hope can attract a broad cross-section of voters who want to move on from President Trump. But his long political record is expected to face intense scrutiny, particularly from younger, more progressive Democrats.

The details: We examined where Mr. Biden stands on the issues, and how his views have changed over nearly 50 years in Washington.

Closer look: The Democratic Party has grown increasingly progressive and diverse since Mr. Biden first ran for the Senate in 1972.

President Trump vows to fight “all the subpoenas”

The Trump administration has made a series of moves this week to block multiple investigations, which could redefine Congress’s power to conduct oversight of the executive branch as well as presidents’ power to keep government affairs secret.