The White House announced a deal Thursday with Abbott Laboratories to produce 150 million rapid coronavirus tests that will allow users to obtain results in 15 minutes from a small card.

The announcement of the $760 million agreement came just hours before President Trump delivered his nomination acceptance speech at the close of the Republican National Convention.

“This is a major development that will help our country to remain open, get Americans back to work, and kids back to school!” White House press secretary Kayleigh McEnany tweeted late Thursday afternoon.

The move is the federal government’s biggest step into testing for the virus that has killed more than 177,000 Americans and infected more than 5.8 million. Almost since the pandemic arrived on U.S. shores in January, Trump has insisted that testing was mainly the province of state and local authorities.

It comes five months after Trump and top health officials said they would turn to private pharmaceutical companies to develop point-of-care tests, with the Food and Drug Administration working, in particular, with Abbott.

“We want as much rapid testing as we can get,” said Carl Bergstrom, a biologist at the University of Washington and an infectious-disease expert. “It’s a step in the right direction.”

Bergstrom said a key question will be how the administration distributes the tests and ensures they reach the places where they are needed most.

Earlier this week, the Centers for Disease Control and Prevention changed its guidance on testing at the direction of the White House coronavirus task force, stating that people who have been in close contact with an individual with covid-19, the disease caused by the virus, but who do not have symptoms “do not necessarily need a test.” Previously, the public health agency had advised anyone in close contact with an infected person to be tested for the virus.

Though antigen tests like this one are largely used to screen large numbers of people to find those who may be infected, the FDA said the Abbott test “has been authorized for use in patients suspected of COVID-19 by their healthcare provider within seven days of symptom onset.”

The antigen test has a greater chance of a false negative result than the more reliable polymerase chain reaction, or PCR, test. The FDA said users may need a second test to confirm a negative result.

The United States has so far conducted 74 million coronavirus tests, according to the Covid Tracking Project, a volunteer organization launched by the Atlantic magazine that is dedicated to collecting data about the U.S. outbreak.

Trump has repeatedly insisted, falsely, that the large number of tests is why the United States appears to be faring poorly against the virus when compared with other developed nations. In fact, the United States, with about 4 percent of the world’s population, has more than 20 percent of the planet’s covid-19 deaths.

On Wednesday, a day before Trump’s convention speech, the FDA issued an emergency-use authorization for the $5 Abbott BinaxNow tests. Using antigens, they will work something like a pregnancy test. Health-care providers will swab a patient’s nose and apply the sample to a credit-card-size card with a testing chemical. After 15 minutes, health-care providers will read the card. One line means negative, two lines means positive.

This test is aimed at schools, nursing homes, doctor offices and other places where people need to be tested in a short time. Abbott hopes to make as many as 50 million tests available monthly in the United States at the start of October.

White House officials did not immediately elaborate on how the tests will be distributed or offer details on other logistics. They did not respond to a request for clarification on how the release of millions of new tests squares with the new CDC testing guidelines.

Scott J. Becker, executive director of the Association of Public Health Laboratories, said that as a medical device, the new test would require a certificate under the Clinical Laboratory Improvement Amendments or a waiver from the Centers for Medicare and Medicaid Services.

Amy Goldstein and Carolyn Y. Johnson contributed to this report.