Democratic U.S. presidential candidate Senator Bernie Sanders is accompanied by his relatives, including his wife Jane, as he addresses supporters at his Super Tuesday night rally in Essex Junction, Vermont, U.S., March 3, 2020

Bernie Sanders and Joe Biden's presidential campaigns canceled rallies set for Cleveland on Tuesday night due to coronavirus concerns, the first disruptions the outbreak has caused in the 2020 Democratic primary.

In separate announcements, the Democratic presidential contenders' campaigns said they exercised caution about holding large public gatherings after hearing guidance from public health officials. Both the Sanders and Biden campaigns thanked supporters who planned to attend the events on a crucial day in the race to decide who faces President Donald Trump in November.

In a statement, Sanders communications director Mike Casca said the Vermont senator's campaign will evaluate future events "on a case by case basis."

Biden communications director Kate Bedingfield said the campaign will "make announcements about future events in the coming days." The Democratic front-runner plans to deliver remarks at the National Constitution Center in Philadelphia at 9:30 p.m. ET.