One possible explanation is that Obama is trying to shift the spotlight away from Biden by making this comment.
“I believe that Joe Biden’s vision of a generous, prosperous, and united America that provides opportunity for everyone will be on full display at the Democratic Convention in August,”
said the senator. “And I expect that every single one of us are prepared to carry that message of hope and progress forward into November and beyond.”
The Telegraph reports that senior Democrats Hakeem Jeffries, Chuck Schumer, and Nancy Pelosi all praised Biden’s decision but did not explicitly endorse Harris.
On August 19, party delegates will convene at the Democratic National Convention to vote on Biden’s replacement, and the official choice will be announced then.