Psaki, during her press briefing Wednesday, declined to go into details on what the action would entail but said the president would have "more to say" tomorrow.
Earlier Wednesday, Politico first reported that an executive order is coming – after three recent mass shootings in Boulder, Colorado, Atlanta, Georgia, and Orange, California.
Sources told the outlet Biden would begin the process of requiring those who buy "ghost guns," firearms that lack serial numbers since they’re sold in pieces and put together at home, to undergo background checks. Biden is expected to be joined at the event by Attorney General Merrick Garland.
It’s not clear what other action will be announced. Last week 100 House Democrats wrote to Biden urging him to take action on concealed assault-style rifles.
Biden has called for a ban on "assault weapons" and high-capacity magazines, which would likely take an act of Congress. He could, however, use regulatory authority to restrict access to such guns.
"I got that done as a senator. It brought down mass shootings, we can do it again," Biden said last month. "We can ban assault weapons and high-capacity magazines in this country once again."
"I think that President Biden will try to get away with as much as he can with executive orders," Alan Gottlieb, founder of the Second Amendment Foundation, told Fox News, adding that his organization is "very prepared to go to court" if Biden oversteps.
"What we’re expecting him to do is anything with foreign commerce – if the firearm is being imported in or magazine or ammo is being imported in – he could by executive order try to do something in that nature," Gottlieb continued.
Gottlieb said Biden could use the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) to tighten regulations. Biden has yet to nominate a director for the ATF.
The Biden administration has also pushed for legislative action, calling on the Senate to pass two bills that recently made their way through the House.
The bills expand federal gun background checks on all firearms sales and extend the background check review period from three days to a minimum of 10 business days. One bill would close the "Charleston loophole," in which a gun sale is allowed to proceed if the background check is not completed in three days.