Ohio’s governor has ordered polling stations in the state to close as the Covid-19 pandemic disrupts vast swathes of American life.
The state was one of four due to hold Democratic primary votes on Tuesday.
However, Governor Mike DeWine has closed polls following a state Supreme Court decision allowing the vote to be postponed.
Other Democratic contests to choose a nominee to take on President Donald Trump have also been disrupted.
Mr DeWine made the decision to close in-person voting sites soon after Americans were warned by the White House to avoid groups of 10 or more.
On Tuesday, another Republican governor, Larry Hogan of Maryland, said his state’s primary contest would be postponed from 28 April to 2 June.
Millions of people are sheltering in their homes as the Covid-19 transmission rate grows.