What a difference eight years makes.
This time, Clinton is expected to face little primary competition — and the left-leaning entertainment industry is poised to become a major source of campaign cash.
Clinton has already lined up support from some of the industry's most prominent leaders, including Jeffrey Katzenberg, Steven Spielberg and "Girls" creator Lena Dunham.
"I've got an inbox full of people offering to hold events for Hillary," said Andy Spahn, whose political consulting firm Gonring, Spahn & Associates advises Katzenberg and Spielberg. "There is great respect and admiration and excitement around Hillary and also a very clear understanding of what the stakes are."
Hollywood is considered one of the most important sources of money for Democratic presidential candidates — a single fundraiser for President Obama at the home of actor George Clooney in 2012 famously raised $15 million for Obama's reelection campaign, among the biggest single-night hauls in political fundraising history.
Some prominent Democratic backers are still on the fence. But political consultants said they expect that Hollywood power players — most of whom are squarely on the left — will come out in full support for a Clinton presidency.
"The passion for ensuring the election for a Democrat will be extremely high — it will almost be an obsession," Los Angeles-based Democratic political strategist Donna Bojarsky said. "Republicans have both houses of Congress, and we are being treated to the prospect of the tea party and right-wing Republicans advocating things that are distinctly unpopular around here."
In the 2008 Democratic primary race, several high-profile Hollywood figures, including mogul David Geffen and Katzenberg, supported Obama. It led to bruised egos in the Clinton camp given the candidate's long-standing ties to the industry.
In widely publicized comments, Geffen, once one of Bill Clinton's biggest supporters, called then-New York Sen. Hillary Clinton an "incredibly polarizing figure." He criticized her husband's 2001 pardon of fugitive financier Marc Rich and suggested that the former president's personal habits would damage his wife's campaign.
"Everybody in politics lies, but they do it with such ease, it's troubling," Geffen said of the Clintons in an interview with New York Times columnist Maureen Dowd in 2007.
The comments caused such a stir that Hillary Clinton's campaign chairman, Terry McAuliffe, warned that Clinton would remember those who did not back her. "You're either with us or against us," McAuliffe told potential donors during a dinner at the home of media mogul Haim Saban.
A spokeswoman for Geffen said he would vote for Clinton but declined to comment further.
Democratic political consultant Chris Lehane, who served as an attorney in the Clinton White House, believes that Hollywood donors are now united by a sense of common purpose.
"In 2008, there were two green-light actors vying for the lead role," Lehane said. "In 2016, there is one green-light actor vying for the lead role, which makes it very easy for those in show business to know where they are going on this."
Clinton's strong record of support for Israel — a topic of great concern to Tinseltown players such as Saban — should help the former secretary of state, he added.
Also, the chance to elect a female president could prove a rallying point for women in the entertainment industry.
"It's a moment for women in Hollywood — just like women everywhere else — to show their daughters that this is possible," Bojarsky said.
Some prominent Democrats, however, aren't yet ready to jump on board the Ready for Hillary campaign. They would prefer a more contested Democratic primary rather than handing the nomination to Clinton.
"I hope Elizabeth Warren comes in and does a primary, because I think that would be good," actor Mark Ruffalo said at the Hollywood premiere of "Avengers: Age of Ultron." "If Hillary is nominated, I will be pulling for her."
In addition, left-leaning liberals view Clinton as too moderate on important issues, such as climate change and defense.
Still other Democrats are loyal to Obama and would like to see him accomplish some of his remaining goals, rather than publicly rallying around Clinton.
Some high-profile Hollywood Democrats — such as Netflix Chief Content Officer Ted Sarandos and his wife, Nicole Avant, a former U.S. ambassador to the Bahamas — have yet to publicly declare their support for Clinton.
"Key players are demonstrating a range of views about her running, from caution to optimism, and at this point offering armchair analysis of her playbook and campaign strategy," said Paul Pflug, whose firm Principal Communications Group/Sky Advisory advises clients on political and philanthropic goals. "But through it all, the majority of this company town will ultimately rally around Clinton."
Planning has already begun for multiple fundraisers for Clinton in Los Angeles, Chicago and New York. They could begin as early as next month.
Katzenberg is a big supporter of Clinton and "will play a major role on her behalf," said Spahn, the political consultant. He said it was too early to discuss details of upcoming fundraising events.
Democrats have long relied on the generous backing of entertainment industry heavyweights, a fact that Republican critics have used to show their opponents as being out of touch with regular Americans.
In early 2007, Geffen, Spielberg and Katzenberg kicked off the race for campaign dollars with a reception for Obama's presidential exploratory committee at the Beverly Hilton Hotel. One high-profile Obama event took place at the Santa Barbara home of Oprah Winfrey.
According to the Center for Responsive Politics, Jeffrey and Marilyn Katzenberg's political contributions totaled $3.5 million in the 2011-12 cycle. Donations from Spielberg and his wife, Kate Capshaw, totaled $1.3 million, most of which went to the political action committee supporting Obama's reelection, Priorities USA Action. Comedian Bill Maher donated $1 million to the organization.
For the entire 2008 election cycle, the entertainment industry raised about $51 million, with 79% of the total going to Democrats, according to the Center for Responsive Politics. The industry raised nearly $66 million for the 2012 cycle, with 73% for Democrats.
Even in nonpresidential election years, Obama has not shied away from political campaign events in Southern California. In October, the president attended a fundraiser at actress Gwyneth Paltrow's home in Brentwood, where about 200 supporters gathered during the contentious 2014 midterm elections.
Clinton supporters have been out raising money for more than a year. They've asked potential donors to give to the Clinton Foundation or the Ready for Hillary PAC.
Beyond raising cash, Clinton is already gaining some celebrity traction on social media, which is where she announced her candidacy. Many took to Twitter to show support.
"This is Hillary reading a text from me that says 'with you every step of the way, gurl' #mypresident," Dunham tweeted with a link to an Instagram photo of Clinton looking down at her cellphone while wearing sunglasses.
Times staff writers Meg James, Ryan Faughnder, Saba Hamedy and Amy Kaufman contributed to this report.