(CNN) One of the Democratic Party's most prolific fundraisers says he has pledged to raise campaign money for rising political star Beto O'Rourke should the Texas Democrat seek the presidency in 2020.

Chicago financier Louis Susman, who served as finance chairman of John Kerry's 2004 presidential bid and was an early backer of President Barack Obama's White House ambitions in 2008, told CNN in a telephone interview he has met with O'Rourke on a number of occasions and that he is encouraging him to run.

"It's time to pass the torch to a new generation," said Susman, a former US Ambassador to United Kingdom in the Obama administration. "I have nothing against the Bidens and Kerrys of the world and all of these senators that are looking at it, but I think the Beto example is what inspired people and what we are going to need."

The support from Susman marks the latest sign of Democratic enthusiasm for O'Rourke, a three-term congressman who raised record sums in his Senate bid and came within 3 percentage points of toppling Republican Sen. Ted Cruz in traditionally red Texas. A CNN tally also shows dozens of top Obama bundlers provided financial support to O'Rourke's unsuccessful bid.

But elite Democratic fundraisers interviewed by CNN in recent days -- some of whom have longstanding ties to former Vice President Joe Biden -- say they still are weighing their options in the presidential race, even if they donated to O'Rourke's Senate campaign. And many are calling for a competitive primary to send a battle-tested Democrat into the general election against President Donald Trump, who defied both political convention and better-funded candidates to capture the White House in 2016.

"What I'm looking for this time is someone who can win Ohio, Michigan, Pennsylvania and Florida," Gary Hirshberg, the co-founder of organic yogurt producer Stonyfield Farm, said, ticking off crucial swing states Trump won two years ago.

Hirshberg, a top fundraiser for Obama's campaign and Hillary Clinton's 2016 White House bid, donated $500 to O'Rourke's Senate campaign.

But he said that doesn't translate into automatic support for a presidential bid should O'Rourke run. Instead, he is taking a close look at other, more experienced Democrats, including Ohio Sen. Sherrod Brown, who won a third term last month in a state Trump captured by eight percentage points, and John Hickenlooper, the former two-term governor of Colorado.

"I don't just need someone who can rock a rally," Hirshberg said. "I'm looking for somebody who demonstrates executive prowess and deep substance."

Campaign bundlers, such as Susman and Hirshberg, play a crucial role in presidential campaigns because they can tap their extensive networks of business associates, family and friends to help collect or "bundle" the huge sums needed to mount a White House bid that could surpass the $2 billion mark for the parties' eventual nominees and the groups supporting them.

A raft of potential Democratic contenders will compete for their financial backing. In addition to O'Rourke, the potential Democratic field includes governors, at least seven US senators, sprinkling of business executives, and Obama administration veterans, such as former US Housing and Urban Development secretary Julian Castro and Biden, who told a Montana audience this week that he's the "most qualified person in the country to be president."

At least two billionaires who can help fund their own campaigns, California environmental activist Tom Steyer and former New York mayor Michael Bloomberg, are also weighing bids.

But a CNN analysis shows O'Rourke has won the attention of some of Obama's biggest financial backers. At least 59 individuals who raised $500,000 or more for Obama's re-election in 2012 donated to O'Rourke's 2018 campaign, CNN's tally finds. That surpasses the number of top bundlers who contributed to the federal fundraising vehicles established in this election cycle by other Democrats who have either declared their 2020 intentions or are pondering bids.

For instance, only about two dozen people in the highest echelon of Obama bundlers had written checks to a fundraising committee, American Possibilities PAC, established by Biden to support other Democrats in the midterms, according to the review of donations reported to the Federal Election Commission through early this week.

O'Rourke has not declared his 2020 intentions, and a campaign aide declined to comment.

No "coronation"

In interviews, Democratic donors say they want a winner.

Rusty Rueff, a philanthropist and veteran of California's tech industry, is among the top Obama bundlers who donated to O'Rourke's Senate campaign, but he's made no choice in the presidential race and instead is rooting for a wide-open fight for the Democratic nomination in 2020.

"I felt like we went through a coronation, not a primary," he said of the 2016 presidential battle that featured Clinton and just four other contenders on the early debate stages. "Because of that, the Secretary (Clinton) never got a chance to have flushed out and taken care of many of the issues that needed to be taken care of before she went to the general election."

Chief among them, according to Rueff: The controversy over Clinton's use of a private email server as secretary of state, which became a rallying cry for Trump and his allies in the general election.

"In retrospect, the day that Bernie Sanders said he was tired of the 'damn emails' was a mistake for the party and for her," said Rueff, referring to Sanders' dismissal of the email controversy during the first Democratic primary debate in October 2015.

Rueff said he's seeking a nominee who's focused on boosting the fortunes of working-class Americans and who offers a "kindler and gentler" approach to politics.

But at the end of the day, he said: "My only choice is someone who can beat Donald Trump."

Other elite fundraisers say their decisions may be months away.

Robert Wolf, the former chairman and CEO of UBS Americas and a leading fundraiser in the Obama and Clinton campaigns, donated to $1,000 to O'Rourke's campaign and $5,000 to Biden's political action committee.

But Wolf said he's still weighing his options and has met with "several individuals over the last month" who are considering White House bids. He declined to name those potential candidates.

Wolf, who now runs his own economic consulting firm, said he may provide initial financial support to several contenders to help Democrats build a large and competitive field.

"Do I want 25 candidates? No," he said. "But if there are a dozen strong candidates and there's truly a primary where people get to voice their views and concerns, that's a good thing."

Waiting for Biden?

Other Obama bundlers who donated to O'Rourke say they still await Biden's next move.

William Freeman, the co-founder of a Nashville real-estate investment and management company, donated to $350 to O'Rourke's campaign, federal election records show.

He praised O'Rourke for injecting "adrenaline and excitement" into a longshot bid for Democrats in Texas but said he's still hoping for a 2020 contender with a longer track record in politics. That includes Minnesota Sen. Amy Klobuchar, Clinton or a "wild card," such as former Tennessee governor Phil Bredesen, who lost a Senate bid last month to Republican Marsha Blackburn.

But if Biden entered the contest, "it would be hard for me not to get behind him," Freeman added. He said the former vice president offers a more "predictable" approach to governing than Trump does.

Richard Harpootlian, a former South Carolina Democratic Party chairman and prominent Biden supporter, also donated to O'Rourke's Senate campaign, along with those of several other potential 2020 contenders, including Klobuchar and Brown, federal records show.

But Harpootlian said he remains a stalwart Biden backer.

"Joe Biden is the only guy in the field right now, man or woman, black or white, young or old, that can win against Donald Trump in 2020," he said. "I'm with Biden and will be with Biden until and unless Biden says he's not running."