NEW YORK (Reuters) - The 2020 U.S. Census, the decennial tally that helps determine political representation and federal aid, will be extended by two weeks, a census official said on Friday, as the coronavirus wreaks havoc on the bureau’s ability to send workers into the field.

In a call with reporters on Friday, Tim Olson, the U.S. Census Bureau’s field operations director, said completion of the bureau’s door-knocking campaign would extend from July 31 to Aug. 14.

The announcement comes two days after the bureau said it would halt earlier field operations that were already ongoing, such as counting the homeless, for two weeks to stem the spread of the virus that has infected more than 17,000 in the United States and 255,000 worldwide. [nL1N2BB36X]

The delays do not impact households’ ability to fill out the census. They can do so online at my2020census.gov, using a unique 12-digit code that was sent to each household by mail this month.

The bureau traditionally sends thousands of workers into the field to knock on doors of households who do not answer the tally voluntarily. The start of that operation had been set to begin in mid-May, but will be delayed until May 28, Olson said, adding that its completion date would also be delayed by two weeks.

The population data collected determines how the U.S. Congress and state legislatures divvy up voting districts, and guides the federal government in allocating $1.5 trillion a year in aid.

The 2020 edition already faced threats to accuracy, including fear in some immigrant communities of providing information to the federal government.

The coronavirus adds another layer of uncertainty. “Continued disruption of census plans” would “increase the risk of census results that won’t be acceptably accurate or fair,” said Terri Ann Lowenthal, a consultant and former congressional staffer overseeing census matters.