<a href="https://www.nytimes.com/2020/03/14/us/politics/election-postponed-canceled.html" target="_blank" rel="noopener noreferrer">Could the 2020 Election Be Postponed? Only With Great Difficulty. Here’s Why.</a>  <font color="#6f6f6f">The New York Times</font>

With Louisiana delaying its primary vote, we answer six key questions about holding elections in a crisis. And no, a president cannot cancel an election with executive authority.

The November general election date is set by federal law, and to change it would mean legislation enacted by Congress, signed by the president and subject to challenge in the courts.Credit…Doug Mills/The New York Times

The coronavirus outbreak is inflicting new disruptions on the 2020 presidential campaign by the day, but few compare to Louisiana’s decision on Friday to reschedule its upcoming primary election.

It was a highly unusual development in an American political campaign, though not an entirely unprecedented one.

So how much disruption can voters expect in the coming months? And how freely can local, state and federal authorities switch up the timing and other details of elections? We took a crack at answering some of the questions that may be on your mind.

Louisiana’s secretary of state, R. Kyle Ardoin, a Republican, asked Gov. John Bel Edwards, a Democrat, to postpone the state’s April 4 primary by about two months because of concerns about the spread of the coronavirus.

The two men are permitted to do so by a Louisiana law that allows the governor to reschedule an election because of an emergency, so long as the secretary of state has certified that an emergency exists.

No. Or at least, not yet.

The four states with elections coming up on Tuesday — Florida, Ohio, Arizona and Illinois — have taken other precautions to make voting safer without shifting the date of their primaries. It is possible, however, that some later-voting states could follow Louisiana’s example.

While a last-minute change like Louisiana’s is highly unusual, states have broad autonomy to define the timing and procedures for primary elections. The exact process for setting primary dates varies from state to state. That is why a number of states changed the dates of their primaries and caucuses between 2016 and 2020, and why Republicans in several states were able to cancel their 2020 primary elections to minimize intraparty competition for President Trump.

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But the Democratic Party also has its own rules requiring that all primary elections be completed by June 9, and that all delegates to its national convention in Milwaukee be selected by June 20. Any states that defy that timetable — including Louisiana — could be penalized by the national party with a reduction in their delegate count.

Only with enormous difficulty.

The date of the general election is set by federal law and has been fixed since 1845. It would take a change in federal law to move that date. That would mean legislation enacted by Congress, signed by the president and subject to challenge in the courts.

To call that unlikely would be an understatement.

And even if all of that happened, there would not be much flexibility in choosing an alternate election date: The Constitution mandates that the new Congress must be sworn in on Jan. 3, and that the new president’s term must begin on Jan. 20. Those dates cannot be changed just by the passage of normal legislation.

After Louisiana’s announcement on Friday, Marc Elias, the prominent Democratic election lawyer, knocked down what he described as a wave of queries about whether the November election could be similarly revised.

“I am getting a lot of questions about the November election,” Mr. Elias wrote on Twitter. “While states can set their own primary days, the federal general election is set by federal statute as the the [sic] Tuesday following the first Monday in November. This date cannot be changed by a state nor by the President.”

No. The president has a lot of power, but when it comes to elections he is far more constrained than the governor of Louisiana.

While the date of the presidential election is set by federal law, the procedures for voting are generally controlled at the state level.

That’s why we have such a complicated patchwork of voting regulations, with some states allowing early and absentee voting; some permitting voting by mail or same-day voter registration; others requiring certain kinds of identification for voters; and many states doing few or none of those things.

So it is possible that states could revise their voting procedures in response to a public health crisis, perhaps by making it easier to vote by mail or through various absentee procedures that would not require people to cluster together on one particular date.

Washington State, a focal point for the coronavirus outbreak in the United States, has conducted elections by mail for years, and its presidential primary on March 10 was able to unfold without disruption.

The federal government could also take steps to mandate or encourage different voting procedures, without changing the timing of the election. Richard L. Hasen, an election law expert and professor at the University of California, Irvine, has proposed that Congress require states to offer “no excuse absentee balloting” for the general election, so that anyone can opt to vote by a method besides in-person voting on Election Day.

Yes, at the state and local level.

Perhaps most notably, the Sept. 11, 2001, terror attacks came on the morning of a municipal primary election in New York City, and the state Legislature passed emergency legislation postponing the election by two weeks. In 2017, some municipal elections in Florida were briefly delayed because of Hurricane Irma.

It was reported in 2004 that some Bush administration officials had discussed putting in place a method of postponing a federal election in the event of a terrorist attack. But that idea fizzled quickly, and Condoleezza Rice, then the national security adviser, said that the United States had held “elections in this country when we were at war, even when we were in civil war. And we should have the elections on time.”

    • What is a coronavirus?
      It is a novel virus named for the crownlike spikes that protrude from its surface. The coronavirus can infect both animals and people and can cause a range of respiratory illnesses from the common cold to lung lesions and pneumonia.
    • How contagious is the virus?
      It seems to spread very easily from person to person, especially in homes, hospitals and other confined spaces. The pathogen can travel through the air, enveloped in tiny respiratory droplets that are produced when a sick person breathes, talks, coughs or sneezes.
    • Where has the virus spread?
      The virus, which originated in Wuhan, China, has sickened more than 142,100 in at least 113 countries and more than 5,300 have died. The spread has slowed in China but is gaining speed in Europe and the United States. World Health Organization officials said the outbreak qualifies as a pandemic.
    • What symptoms should I look out for?
      Symptoms, which can take between two to 14 days to appear, include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Milder cases may resemble the flu or a bad cold, but people may be able to pass on the virus even before they develop symptoms.
    • What if I’m traveling?
      The State Department has issued a global Level 3 health advisory telling United States citizens to “reconsider travel” to all countries because of the worldwide effects of the coronavirus. This is the department’s second-highest advisory.
    • How long will it take to develop a treatment or vaccine?
      Several drugs are being tested, and some initial findings are expected soon. A vaccine to stop the spread is still at least a year away.