“People should not be forced to put their lives on the line to vote, which is why 15 states are now following the advice of public health experts and delaying their elections. We urge Wisconsin to join them,” Sanders said in a statement. “The state should delay Tuesday’s vote, extend early voting and work to move entirely to vote-by-mail. While we wait for a decision, we urge our supporters to vote-by-mail.”

Polling stations in Wisconsin have been forced to close due to a lack of workers. The National Guard is reportedly sending members to fill the void.

The last round of primaries took place on March 17 in Arizona, Florida and Illinois. There were questions even then about whether those elections should move forward and the outbreak has only worsened since then. There is a growing sense among political leaders that elections should only be held by mail at the moment, if they’re going to be held at all.