WASHINGTON — President Joe Biden on Monday pledged the full support of the federal government to states facing surges in COVID-19 cases from the more-transmissible omicron variant and a run on at-home tests.

Joining a regular meeting between his coronavirus response team and the National Governors Association, Biden said, “My message is: if you need something, say something, and we are going to have your back any way we can.”

Biden acknowledged long lines and chaotic scenes as Americans sought out testing amid the case surge and as they looked to safely gather with family and friends over the holiday.

He referenced his administration’s plan to make 500 million rapid tests available to Americans beginning next month through an as-yet-to-be-developed website.

A White House official said the new tests would come from new manufacturing capacity and wouldn’t interfere with existing supply chains.