LOS ANGELES — As dusk descended Thursday over the posh hills of Brentwood, actor Martin Sheen gathered with his former “West Wing” co-stars Bradley Whitford and Mary McCormack to open up their checkbooks for Pete Buttigieg.

Hollywood mogul Rob Reiner was also there for the event at actress Gwyneth Paltrow’s home, along with President Obama’s former Deputy Attorney General Sally Yates and several former ambassadors who showed up to get a glimpse at the South Bend, Indiana mayor, two sources with knowledge of the event told NBC News.

It was just one of nearly a dozen high-rolling fundraisers that Buttigieg has been holding this week in Los Angeles, San Diego and finally San Francisco, where he is collecting money Friday from Silicon Valley execs at a trio of fundraisers — including one hosted by Michelle Sandberg, sister of Facebook’s Sheryl Sandberg, and her venture capitalist husband Marc Bodnick.

The money push also included a colorful stop at West Hollywood’s iconic The Abbey nightclub, where Buttigieg’s blue-and-yellow logos were bathed in blinking neon lights as he and his husband, Chasten, made their case.

As he works to solidify his place in the top tier of Democratic presidential candidates, Buttigieg is making inroads with the same coalition of West Coast Democratic donors who provided critical fuel to Barack Obama’s 2008 campaign and Hillary Clinton’s eight years later: The Hollywood glitterati, tech entrepreneurs and major LGBT donors.

The early success in attracting attention from bold-name donors in the party has intensified Buttigieg’s contest with his competitors – particularly Joe Biden, who was also collecting massive sums this week from Hollywood types, and Kamala Harris, the California senator and former state attorney general whose ties to the state and its donor base run deep.

Biden’s swing through Los Angeles included a fundraiser hosted by Google CEO Eric Schmidt and one with former Ambassador James Costos, who just a day later attended Buttigieg’s fundraiser. And LinkedIn co-founder Reid Hoffman plans to host a California fundraiser this month for Cory Booker.

For Buttigieg, the support from well-heeled donors also follows newfound interest from pop culture icons like Oprah Winfrey whose support for Obama helped raise his national profile in 2008, particularly among Americans who pay less attention to the daily political horse race. Winfrey hasn’t endorsed a candidate this year but said recently that she had encouraged director Steven Spielberg to take a look at Buttigieg.

Ami Copeland, Obama’s deputy national finance director in 2008, said attention from the high-dollar donor class is “very important for those coming out of the gate” who need to prove their ability to raise the kind of money needed to win. Still, he warned that it mustn’t come at the expense of courting the grassroots donors who help mobilize votes on the ground.

“It can’t be only the high-dollar people,” Copeland said. “It's a good proof-point, but I don’t think it carries as much weigh in the early states. Iowa voters don’t care as much who some of the Hollywood moguls are behind.”

A key difference this year compared to past elections, as least so far, is that major donors are shopping around and donating to multiple candidates while they keep their options open about whom to ultimately support, rather than backing a specific candidate exclusively from the start, two Democratic consultants tell NBC News.

“In terms of ‘Hollywood’ donors, they’re just all over the place. Most donors are giving to more than one candidate,” said Noah Mamet, a major Democratic donor and former ambassador to Argentina who serves as a liaison for Democrats to the Hollywood community. “Many donors want to see multiple candidates seriously competing for the nomination."

For Buttigieg, an unknown on the national political stage until recently, the interest from well-known Democrats illustrates how a campaign that once seemed unlikely to be competitive is now perceived as viable by elements of the Democratic establishment.

On his California swing this week, he also attended fundraisers hosted by Isaac Pritzker of the billionaire Pritzker family that played a major role in Obama’s ascent, and by Vicki Kennedy, the wife of Max Kennedy, whose father was former Sen. Robert Kennedy. His fundraiser at Paltrow’s home also included Nicole Avant, who played a critical role raising millions in Los Angeles cash for Obama in 2008 and was later named as his ambassador to the Bahamas.

And while gay and lesbian donors rallied behind Obama’s 2012 re-election campaign and Clinton’s campaign in 2016, many are now sending their checks to Buttigieg, the first competitive presidential candidate to be openly gay. As the beer flowed Thursday at his fundraiser in West Hollywood, his husband, Chasten Glezman, told the sold-out crowd what it was like to walk through an airport this week and see himself and his husband on the cover of Time Magazine with the headline “First Family.”

“That will never go away,” Glezman said. “That’s for every kid to see that you too can run for president.”

His ascent has created an unexpected conflict for LGBT donors who have long felt loyalty toward more veteran Democratic politicians like Biden who supported same-sex marriage and other gay rights issues when it was far less popular to do so. Donors who had expected to back Biden, Elizabeth Warren or Kirsten Gillibrand now face the question of whether to miss out on taking part in support a history-making candidate.

Jon Cooper, a major Democratic donor who was on Obama’s National Finance Committee, said he pushed Biden hard in 2016 to run for president, and although he feels internal conflict, is sticking with him in 2020, owing in part to Biden’s 2012 declaration of support for same-sex marriage on NBC’s "Meet the Press" that predated even that of Obama.

“Joe Biden basically broke the dam. He made it safe for others to wade into that water and take that position. So there is a special place in the hearts of most folks in the LGBT community,” Cooper said. “But there was a part of me early on that really wanted to be able to back Mayor Pete, who brings an awful lot for the LGBT community to be proud of.”

And while he’s made clear his allegiance is to Biden, just recently Cooper’s phone rang with a question from the Buttigieg campaign: Would he be willing to sit down with the candidate?

“I said I’d still love to meet with Mayor Pete,” he said.