Since Harris' departure, Newsom had faced some pressure to name a Latino or a Black woman as a replacement. Karen Bass or Barbara Lee to replace her.
Newsom praised Padilla, who is known as an ally of the governor, in a statement on Tuesday for "his tenacity, integrity, smarts and grit".
"It is ok to simultaneously be sad that there will be no black woman in the US Senate, and happy about an Alex Padilla appointment", wrote Stephanie Clay, a comic-book writer from Houston, summing up the views of many Democrats on social media. "It's a terribly insensitive decision" with the nation in the midst of a reckoning over racial injustice.
"Through the looking glass of California politics, our state's top elections official will now become a U.S Senator without an election", Republican state Assemblyman Kevin Kiley, a frequent critic, tweeted. She says plans for rationing care are not in place yet, but they need to be established because "the worst is yet to come".
He'll hold the Senate seat through 2022, when he will have to run for reelection. Padilla's current job was also being eyed by other possible contenders, who could challenge Weber if she is confirmed by the Legislature.
It is expected that Newsom will have to appoint a new state attorney general, as well.
Padilla quickly formed a political committee to begin raising money and released a campaign-style ad introducing himself as the new senator. He has an engineering degree from the Massachusetts Institute of Technology, and he previously served on the school's governing board.
Padilla served as a member of the Los Angeles City Council from 1999 to 2006 and as a California state senator from 2006 to 2014, according to Ballotpedia.
Over Thanksgiving, Newsom and his family went into quarantine after his children were exposed in two separate incidents to someone who had tested positive for the coronavirus.