WASHINGTON — President Joe Biden on Thursday is toughening COVID-19 vaccine requirements for federal workers and contractors as he aims to boost vaccinations and curb the surging delta variant that is killing thousands each week and jeopardizing the nation's economic recovery.

Just weeks after he mandated federal workers get a shot or face rigorous testing and masking protocols, Biden will sign a new executive order to require vaccination for employees of the executive branch and contractors who do business with the federal government, according to a person familiar with the matter.

The word comes ahead of the president's speech Thursday afternoon outlining a six-pronged plan to address the latest rise in coronavirus cases and the stagnating pace of COVID-19 shots just two months after he prematurely declared the nation's "independence" from the virus.

After months of using promotions to drive the vaccination rate, Biden has taken deliberate steps to increase the inconvenience experienced by the unvaccinated, aiming to restore more normalcy to those who have gotten shots. Those penalties and requirements have been carefully calibrated, with Biden resisting imposing some options within his authority, to avoid feeding into partisan backlash to the vaccines. 

It wasn't immediately clear if Biden's order includes exceptions for workers or contractors seeking religious or medical exemptions from vaccination. The person spoke on the condition of anonymity to discuss Biden's plans before they were publicly released. 

Biden is also expected to outline plans to increase virus testing in schools, in an effort to keep them open safely, amid other measures to show that his administration is working to tackle the alarming rise in COVID-19 cases, which Biden has blamed for last month's weaker-than-expected jobs report. He's warned the surge could further imperil the nation's economy as some pandemic safety net protections expire.

Biden has encouraged COVID-19 vaccine requirements in settings like schools, workplaces and university campuses, and the White House hopes the strengthened federal mandate will inspire more businesses to follow suit. On Thursday, the Los Angeles board of education is expected to vote on requiring all students 12 and older to be fully vaccinated in the the nation's second-largest school district.

The Department of Veterans Affairs, Department of Health and Human Services, the Indian Health Service, and the National Institute of Health have previously announced vaccine requirements for much of their staffs, and the Pentagon moved last month to require all servicemembers to get vaccinated.

More than 208 million Americans have received at least one dose of a COVID-19 vaccine, and 177 million are fully vaccinated, but confirmed cases of the virus have shot up in recent weeks to an average of about 140,000 per day with on average about 1,000 Americans dying from the virus daily, according to data from the Centers for Disease Control and Prevention.

An AP-NORC poll conducted in August found 55% of Americans in favor of requiring government workers to be fully vaccinated, compared with 21% opposed.

Most of the spread — and the vast majority of severe illness and death — is occurring among those not yet fully vaccinated against the virus. So-called breakthrough infections in vaccinated people occur, but tend to be far less dangerous.

Compared to the same time last year, the U.S. is seeing about 300% more new COVID-19 infections a day, about two-and-a-half times more hospitalizations, and nearly twice the number of deaths, said Dr. Leana Wen, a former Baltimore health commissioner who comments regularly on the pandemic.

"We cannot accept this to be the new normal," said Wen. If the pandemic continues unabated, it will mean 500,000 deaths a year. "Surely no one wants that."

Wen has been urging the White House to take a stronger line on vaccine requirements, including the use of so-called vaccine "passports" for travel and workplace mandates that leave little wiggle room.

"I want to see the full power of the federal government here, and not more half measures," she said. "I want to see a hard reset from the Biden administration, not more nibbling around the edges."

Federal officials are moving ahead with plans to begin administering booster shots of the mRNA vaccines to bolster protection against the more transmissible delta variant of the virus. Last month Biden announced plans to make them available beginning on Sept. 20, but only the Pfizer vaccine will likely have received regulatory approval for a third dose by that time. Federal regulators are seeking additional data from Moderna that will likely delay its booster approval until October. 

Officials are aiming to administer the booster shots about eight months after the second dose of the two-dose vaccines.