Fears over the spread of coronavirus are changing 2020 presidential campaigns as the remaining candidates must find new ways to connect with voters.

The two Democratic frontrunners and the president have all canceled campaign events to avoid large crowds while officials contend with how to handle debates and high-traffic election locations.

Plus, former Vice President Joe Biden, 77, Vermont Sen. Bernie Sanders, 78, and President Donald Trump, 73, are all in that group of older adults the Centers for Disease Control and Prevention says are at a higher risk of COVID-19 and who are urged to take additional precautions.

All eyes are on the way they are handling voter engagement in a time of uncertainty and a growing number of cases in the United States, not only because of the potential risk to candidates and supporters, but because of the way coronavirus has become a political talking point.

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Here are the ways the coronavirus outbreak, now labeled a global pandemic, is changing the 2020 presidential campaign trail:

Campaign stops turn into remote gatherings

Sanders and Biden both canceled campaign events in Cleveland on Tuesday over public health and safety concerns. There are currently five confirmed coronavirus cases in Ohio, according to a Johns Hopkins University case tracker. Some of those cases are in the same county as Cleveland.

"We are heeding the public warnings from Ohio state officials, who have communicated concern about holding large, indoor events during the coronavirus outbreak,” the Sanders campaign said in a statement.

The Sanders campaign also said future events will be evaluated for safety on a case-by-case basis.

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After canceling its Cleveland event, the Biden camp announced two other campaign stops scheduled in Illinois and Florida would become "virtual events" instead, citing requests by elected officials. Illinois has 23 current cases of the virus while Florida has 27.

On Wednesday, Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases and a member of the White House Coronavirus Task Force, discussed with lawmakers the risks of large gatherings, recommending to lawmakers "that there not be large crowds" and citing NBA games as an example.

The Biden and Sanders camps have also asked staff to begin working from home. In a memo to staff, the Biden campaign said Philadelphia headquarters employees and those in field offices will work from home for two weeks and that the campaign would continue only with small events. Sanders' team said in a statement that all staff would begin working from home and that the campaign won't hold large events or do door-to-door canvassing, instead pivoting to "digital formats."

Trump cancels events after uncertainty over large rallies

The Trump campaign has had to contend with questions about whether the president should continue to hold the massive rallies he is known for amid warnings from officials to avoid large crowds.

The campaign had announced a new Wisconsin event just hours after the Democratic frontrunners announced cancellations on Tuesday, but announced it and two other campaign events would be cancelled Wednesday night "out of an abundance of caution." White House tours have also been suspended. The campaign has no rallies schedule at present.

The decision to cancel Trump's events was announced after Trump gave a national address on coronavirus on Wednesday, announcing the suspension of travel from most of Europe to the U.S. along with measures he wants Congress to take to ease the strain on the economy.

Tim Murtaugh, director of communications for the Trump campaign, had previously dismissed reports that there was any scaling back of the president's events over coronavirus.

"I think that’ll be a decision that’s made literally on a day-to-day basis," Pence told reporters when asked about campaign rallies on Tuesday.

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Democratic debate rerouted from Phoenix to DC

The Democratic debate that was slated for Sunday evening in Phoenix will now be held in Washington, D.C. because of coronavirus concerns and to reduce travel, the Democratic National Committee announced Thursday.

Additionally, Univision anchor Jorge Ramos has stepped down as a moderator of the debate due to potential exposure to the virus, though he is not currently experiencing any symptoms. Univision's Ilia Calderón will replace him.

"Out of an abundance of caution and in order to reduce cross-country travel, all parties have decided that the best path forward is to hold Sunday's debate at CNN's studio in Washington, D.C., with no live audience," DNC communications director Xochitl Hinojosa said in a statement.

The DNC had previously announced there would be no live audience in Phoenix, which will remain true in its D.C. venue, shifting the debate dynamic in the first one-on-one showdown between Biden and Sanders. The traditional live audience usually engages with candidates through cheers, loud expressions of disapproval or even protests.

The DNC said the Biden and Sanders campaigns requested the audience change and that there were no plans to cancel the debate altogether. The debate will also not have the usual press filing center and spin room, where members of the media work and often speak with candidates and their spokespeople after the debate.

Arizona currently has eight active cases of coronavirus, while Washington has 10. Arizona's primary is on Tuesday.

Coronavirus is a new political talking point

As the president's messaging on coronavirus has continued to evolve, Democrats have criticized his handling of the virus' spread. Both Biden and Sanders have knocked the president and advocated for their policy proposals in light of the coronavirus.

"There's no confidence in the president and anything he says or does. He turns everything into what he thinks is a political benefit for himself, but he's actually imploding in the process. But there's a lot of innocent bystanders that are being badly hurt," Biden said on MSNBC. "I wish he would just be quiet... Just let the experts speak and acknowledge whatever they suggest to him is what we should be doing."

Biden released a coronavirus plan on Thursday, saying that Trump is "welcome to adopt all of it." Some aspects of the plan include making the coronavirus test more easily accessible, frequent updates about the pandemic from health care officials and economic relief for families who have been hit by coronavirus. Biden also criticized Trump's travel restrictions.

Trump’s campaign slammed Biden’s remarks, saying the president’s “every move has been aimed at keeping Americans safe, while Joe Biden has sought to capitalize politically and stoke citizens’ fears.”

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Sanders is putting forth Medicare for All, his flagship health care proposal, as a necessity. He spoke on Thursday about his own coronavirus plan and the need for "solidarity" and "love and compassion for all, including the most vulnerable people in our society."

He said the current situation is "a national emergency," and that the U.S. must act accordingly, calling for coronavirus vaccines and treatment to be administered without charge to patients. He also said there should be economic relief for workers who have are sick and must stay home or workers who have been fired, and for service workers whose pay might be affected due to lack of tips.

The Trump campaign on Wednesday accused Biden of canceling campaign events as "an excuse to get off the campaign trail," before Trump's own events were announced as canceled later that night.

Kayleigh McEnany, Trump's campaign spokesperson, said in a Wednesday interview with Fox Business that "the media’s best hope is for Donald Trump to suspend his rallies. They’ve been wanting him to stop this, they know it’s his avenue to speak directly to the American people, so we’re going to follow the president’s lead, we’re not going to cave to the media."

States moving polling places to avoid coronavirus spread

Some states with upcoming elections are moving their polling locations and urging voters to take advantage of vote-by-mail and early voting options where available to prevent the spread of coronavirus to residents of senior homes.

Arizona, Illinois, Florida and Ohio, all states with presidential primaries on Tuesday, have announced changes to polling places, according to local news outlets.

Five polling spots in Maricopa County, Arizona, were moved out of senior living facilities, where residents are at a higher risk for contraction, the Arizona Republic reported.

"Because they were at the homes of older adults and those with serious chronic medical conditions, we made the decision to relocate these polling locations to nonresidential facilities," Maricopa County Elections Department spokeswoman Megan Gilbertson said in a statement, adding that poll workers were also receiving guidance on how to keep locations clean.

In Illinois, the Chicago Board of Elections also planned to move 25 polling spots, some of which were also in senior facilities, according to the Chicago Tribune. The Tampa Bay Times also reported some Florida counties were concerned about poll workers dropping out due to the virus ahead of its Tuesday primary, and that Gov. Ron DeSantis advised the general public should not be allowed to vote at senior center polling sites. And changes will affect at least 100 polling sites in Ohio, according to News 5 Cleveland.

Contributing: John Fritze, Savannah Behrmann, Rebecca Morin, Nicholas Wu, Courtney Subramanian