The Obama transition team and Clinton's Senate office both said the nomination is "on track."
At least two other prominent Democrats were also in the running for the secretary of state job: Richardson and Sen. John Kerry of Massachusetts, the Democratic presidential nominee in 2004.
After a withering campaign, bringing Clinton into Obama's circle was a feat of diplomacy in itself. As candidates, the two competed hard for the nomination, with loyalists trading tough charges.
In March, Obama's team put out a memo challenging Clinton's foreign policy credentials. Greg Craig, who worked in Bill Clinton's State Department, wrote that as first lady she "did not do any heavy lifting with foreign governments, whether they were friendly or not."
Obama recently named Craig to the post of White House counsel.
Obama and Clinton have also represented different factions in the party. He was favored by better-educated, wealthier voters; she by women and a more downscale swath of the electorate.
For Clinton and Obama to have gotten to this point testifies to their political maturity, Boxer said.
"If this were to happen, it's a wonderful signal about our president-elect and also shows that Hillary is willing to forgive and forget, too," Boxer said. "There's no question the campaign was tough. It was very tough. It says a lot about Barack Obama that he's willing to put it aside."
