What to watch: Voters in Maryland will cast ballots in a number of high-profile primaries, including a quixotic Democratic primary for the Senate featuring Chelsea Manning, the convicted leaker, and the crowded Democratic contest to determine who will challenge the state’s Republican governor, Larry Hogan. Read more

There are 14 Democrats competing in the primary for governor, including a former president of the N.A.A.C.P., Ben Jealous, and Rushern L. Baker III, the executive of Prince George’s County. Mr. Hogan, a Republican governor in a blue state, is generally popular among his constituents.

Senator Benjamin L. Cardin, a two-term incumbent, faces a primary challenge from Ms. Manning, a leftist and former Army private who was sentenced to 35 years in prison for leaking classified documents to WikiLeaks.

Mr. Cardin, the ranking Democrat on the Senate Foreign Relations Committee, is expected to defeat Ms. Manning, whose prison sentence was commuted by President Barack Obama in 2017.

— MAGGIE ASTOR