(Adds cancellation of event with Michelle Obama)
WASHINGTON, March 11 (Reuters) - Democratic presidential contenders Joe Biden and Bernie Sanders were left to reassess how to campaign on Wednesday as a spreading U.S. coronavirus outbreak prompted cancellations of election events, including one weeks away.
Biden's campaign, which scored decisive primary victories in Michigan and three other states on Tuesday, canceled a Thursday get-out-the-vote event in Florida. The state, along with Arizona, Illinois and Ohio, will hold primary contests next week.
The winner of the national nominating battle that began in February and ends at July's Democratic National Convention will challenge Republican President Donald Trump in November.
Both the former vice president and Sanders, a U.S. senator, canceled election night rallies on Tuesday, citing recommendations from public health officials to avoid assembling large indoor crowds.
Separately, organizers on Wednesday called off a March 27 rally in Detroit that was to be hosted by former first lady Michelle Obama. The rally, aimed at boosting turnout in November's general election, was canceled "out of an abundance of caution" given the spread of the coronavirus, organizers said.
Biden, the Democratic front-runner, said he would deliver an address on the U.S. response to the virus in his hometown of Wilmington, Delaware, on Thursday.
"This is a matter, this whole coronavirus - is a matter of presidential leadership," Biden told reporters on Tuesday night in Philadelphia. "Later this week, I'll be speaking to you on what I believe the nation should be doing to address this virus."
COVID-19, the disease caused by the virus, is a highly contagious respiratory illness. The number of U.S. coronavirus cases has risen steadily and currently exceeds 1,000, and 28 deaths have been reported, according to a count by Johns Hopkins University.
The outbreak has infected more than 119,000 people and killed more than 4,290 worldwide, according to a Reuters tally. It has pounded financial markets, forced school closures and prompted organizers to cancel concerts, conferences and sporting events.
Exit polls showed that primary voters on Tuesday regarded Biden as a better choice than Sanders to respond to the virus outbreak. In Washington, the state hit the hardest thus far, voters who said they were most concerned about it backed Biden over Sanders by 2-to-1.
Biden, a moderate, and Sanders, a self-described democratic socialist, have both criticized the Trump administration over its response to the outbreak.
The Lawyers' Committee for Civil Rights Under Law urged state election officials to ensure that concerns about the virus did not interfere with upcoming votes.
"States must not wait a moment longer to take real steps to address the impact of the coronavirus on the 2020 election season," the committee said in a statement.
The Democratic National Committee said the next presidential debate, scheduled for Sunday in Arizona, would not have an in-person audience because of health concerns.
(Reporting by Trevor Hunnicutt in Philadelphia and Amanda Becker, Doina Chiacu, Chris Kahn and Jason Lange in Washington; Editing by Scott Malone, Peter Cooney and Jonathan Oatis)
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