Biden on Wednesday told reporters in the Oval Office that decisions by the Texas Gov. Greg Abbott and Mississippi Gov. Tate Reeves to relax COVID-19 restrictions by opening businesses and repealing mask mandates are a "big mistake."

"I think it's a big mistake. Look, I hope everybody has realized by now these masks make a difference," Biden said "We are on the cusp of being able to fundamentally change the nature of this disease because of the way we are able to get vaccine in people’s arms."

Despite the promising increase in vaccinations, Biden said it is not time to relax social distancing measures before enough Americans get the vaccine.

"And the last thing, the last thing we need is the neanderthal thinking that in the meantime everything’s fine, take off your mask, forget it," Biden said. "It still matters."

Biden noted that more than 500,00 Americans have died from the pandemic, saying he keeps a card with that number.

"And it’s critical, critical, critical, critical that they follow the science. Wash your hands. Hot water. Do it frequently. Wear a mask and stay socially distanced. And, I know you all know that," Biden said. "I wish the heck some of our elected officials knew it."

Biden hosted a meeting with bipartisan lawmakers Wednesday afternoon to discuss ways to get to their shared goal of ending cancer "as we know it."

"And what I want to talk with them about today is how we go about taking advantage of the work they’ve done to get us where we are today, because I think we're on the cusp of some real breakthroughs across the board on cancer," Biden said before the meeting.

White House press secretary Jen Psaki previewed the meeting, saying that fighting cancer has "significant personal importance" to Biden, whose oldest son Beau passed away after fighting brain cancer in 2015. During his tenure as vice president, Biden was tapped by former President Barack Obama to lead the fight against cancer.

First lady Jill Biden and newly sworn-in Secretary of Education Miguel Cardona visited Benjamin Franklin Elementary School in Meriden, Connecticut, on Wednesday, to see how the school was adapting to the pandemic. Biden began the tour in a kindergarten classroom, where a teacher at the school showed her plexiglass dividers with pool noodles on the edge, one of the mitigation strategies.

On the next stop on the tour, the first lady visited a sensory room to learn how they modified their approach for special needs students, as well a second-grade classroom, though no students were present.

“I think the teachers are doing such a great job in, you know, meeting the kids where they are, whether that’s in school, whether it’s at home. I mean, really, I think what the teachers have done here to help...America’s children has just been incredible,” Biden said.

-ABC News' Molly Nagle

Harris visited Fibre Space, a woman-owned small business in Alexandria, Virginia, on Wednesday morning to discuss changes small businesses made in the wake of the pandemic and to tout Biden's COVID-19 relief bill.

Fibre Space sells yarn, fibre, and other supplies.

She met with the owner of Fibre Space, Danielle Romanetti, and three employees during the visit, and discussed how Romanetti and her employees have been impacted by COVID-19, including how they have incurred additional child care costs and dealt with uncertainty about their economic futures.

Harris also discussed the importance of passing Biden's American Rescue Plan to get relief to those who need it.