Biden Beams Into Kamala Campaign Event, Says Dropping Out Was 'Right Thing To Do'

President Biden is speaking up after bowing out of the 2024 election and endorsing Kamala Harris ... beaming into a campaign event and saying he made the right choice.

POTUS phoned into his campaign HQ in Wilmington, DE Monday -- which is now Kamala's, -- and told his staffers his decision to leave the race for the White House was "the right thing to do."

Biden says he would have been at Kamala's big event in person if he weren't saddled with COVID ... and he's vowing to be super involved on the campaign trail, stumping for his Vice President as soon as he's able.

The Prez addressed his staffers for about 4 minutes on an audio call ... the first time we've heard from Biden since he abruptly announced Sunday he was passing the torch. At times, his voice was scratchy and he sounded like he was still somewhat under the weather.

Biden thanked his staff for all the hard work they did in getting him the nomination, and he told them they are going to love working for Kamala.

No Zoom or video calls from Biden here, it's purely his voice over a speaker ... so it seems he literally picked up a phone and called from his Delaware beach house, where he's isolating as he fights the virus. Dude's old school.