“If she ran, I would support her — no question,” Mr. Geffen said in an interview. “I think she’s the best candidate currently available for either party.”

Mr. Katzenberg, who joined Mr. Geffen and Steven Spielberg in arranging a $1.3 million fund-raiser for Mr. Obama at Mr. Geffen’s Beverly Hills estate in February 2007, also said he planned to throw his weight behind Mrs. Clinton the next time around.

“If Secretary Clinton makes the decision to run, I expect she’ll have near-unanimous support here,” Mr. Katzenberg wrote in an email. “Hillary represents our best chance to win in 2016, build upon the successes of the Obama administration, and keep the country moving in the right direction.”

The shift reflects enthusiasm about Mrs. Clinton’s prospects for winning the election, but it also highlights the less rose-colored view of Mr. Obama now held by some of his most loyal supporters. “The Hollywood community really came together in the last election and raised an awful lot of money and supported him,” said Felix Schein, a Los Angeles-based political strategist. “I wouldn’t say that’s gone, but the mood is sour.”