Severe winter weather has taken its toll nationwide, including a setback for one of the Biden administration's top priorities: Vaccinating Americans against the deadly coronavirus.

The winter storms have forced vaccination sites to close, and icy roads and snowy conditions have caused a disruption in the supply chain in distributing vaccine doses – it even impacted President Joe Biden's planned trip to Kalamazoo, Michigan, to tour a Pfizer plant producing one of the two approved shots that protect against COVID-19.

Biden was set to meet with workers at the plant Thursday, but instead traveled to the Wolverine State’s Pfizer campus on Friday afternoon. The president was joined by Michigan Gov. Gretchen Whitmer, Pfizer CEO Albert Bourla, and Production Lead Shawn Hamilton during the tour of the 1,300-acre plant, one of three in the United States helping to manufacture the company’s COVID-19 vaccine. 

The group first stopped at the so-called “freezer farm,” a warehouse filled with 350 ultra-cold freezers needed to keep the coronavirus vaccine at the sub-zero temperatures required for shipping and storage. Each of the freezers contains approximately 360,000 doses of the vaccine, according to Pfizer spokesperson Amy Rose.

Biden applauded the site’s 2,240 full time employees and 540 contractors after concluding the tour, saying he traveled to Michigan because he wants the “American people to understand the extraordinary, extraordinary work that's being done to undertake the most difficult operational challenge this nation has ever faced."

Biden added that the White House’s approach to the pandemic will be “guided by science,” saying the previous administration’s failure to do the same led to a shortage of COVID-19 vaccines, limited vaccinators, and insufficient vaccination centers. 

Biden also acknowledged the concerns of those who might be hesitant to get a coronavirus shot, saying Friday’s tour made him all the more confident in the efficacy of the vaccine, saying: "It takes more time to do the check for safety than it does to make the vaccine.” 

"We all know there is a history in this country of having subjected certain communities to terrible medical abuses in the past,” Biden said. “But if there is one message to cut through to everyone in this country it is this: The vaccines are safe. Please, for yourself, for your family, your community, this country, take the vaccine when it's your turn and it’s available.” 

The president also used his speech to call on Republican lawmakers to approve his $1.9 trillion American Rescue Plan, saying in part: "Let me ask them, what would they have me cut? What would they have me leave out?"

Despite his repeated demands that all $1.9 trillion in funding is needed to ensure Americans can survive the pandemic, Biden added that he is “open” to any GOP ideas to make the “plan cheaper.”

Biden’s administration is dealing with the added hurdle of inclement weather, which has delayed coronavirus vaccine deliveries across all 50 states, White House officials confirmed Friday morning. But as shipments resume and scale up, vaccinators in communities across the country are going to have to work overtime to get shots into arms.

The U.S. administered an average of 1.7 million doses per day in the week that ended on Tuesday, evidence that the pace of the vaccination program was picking up. The magnitude of the weather’s impact was not immediately clear because of reporting lags in vaccination data maintained by the Centers for Disease Control and Prevention but it was expected to be significant.

White House press secretary Jen Psaki said the White House was closely monitoring the weather’s impact on vaccine deliveries and working with manufacturers, shipping companies and states to speed their distribution.

The delays were so severe that Massachusetts Gov. Charlie Baker on Thursday suggested he would explore sending his state’s national guard to collect doses from icebound shipping hubs in Memphis, Tennessee, and Louisville, Kentucky.

The Republican governor said the state “may have some real issues with supply delivery this week,” and “we have been told it would be a few days late, based on some of the issues around weather in other parts of the country.”

The Virginia Department of Health reported Thursday that it was expecting delays on about 90% of its expected 120,000 doses this week and warned that the delays could cascade into next week.

“Even if the roads are clear in Virginia, the fulfillment of orders and the movement of those vaccine and ancillary supplies may be delayed in other parts of the country,” the department said in a news release.

In North Carolina, none of the more than 163,000 first and second doses of the Moderna vaccine scheduled to arrive this week have been delivered by Biden’s administration, the state health department said. The state also noted that only a limited number of the nearly 127,000 expected Pfizer vaccines have been shipped.

Oklahoma moved to reschedule vaccine clinics to this weekend, when it expects its 110,000 doses to be delivered, aiming to make up appointments from this week.

The ripple effects extended far beyond areas experiencing winter weather. In Arizona, the bulk of the state’s anticipated shipment of Moderna doses was delayed until early next week, forcing the postponement of some vaccination appointments.

Psaki said the White House was working with shippers to speed deliveries of the vaccines once conditions improved and was encouraging states to extend hours for vaccination clinics once they reopen and to swiftly rebook postponed appointments.

“We want to make sure that as we’ve lost some time in some states for people to get needles in arms, that our partners do all they can to make up that lost ground,” said White House coronavirus coordinator Jeff Zients.

Both the Pfizer and Moderna vaccines must remain frozen during shipping, with the Pfizer shot requiring super-cold storage temperatures. The White House said it was working with shippers to ensure there was no spoilage of doses during the weather delays.

“We're asking states, sites and vaccinators to help us catch up and to get Americans vaccinated,” Andy Slavitt, senior adviser for the COVID-19 Response said Friday. “We're asking the vaccine administration sites to extend their hours even further and offer additional appointments.”

The Associated Press contributed to this report.