About 53 per cent of the more than 1600 attendees who voted in a straw poll on Saturday chose Vance.
Secretary of State Marco Rubio came in second with 35 per cent at the key annual gathering for Republican lawmakers, activists and presidential hopefuls.
CPAC, which is holding this year's event in Grapevine, Texas, draws heavily from the Republican Party's conservative wing. Its annual straw poll is not necessarily a reliable predictor of the eventual nominee.
But the poll offers a snapshot of where the energy currently lies among core supporters of President Donald Trump's Make America Great Again movement, also known as MAGA.
Trump is not eligible to run again in 2028.
Paul Empson, a 58-year-old accountant and evangelical Christian from Fort Worth, Texas, said he voted for Vance because he sees him as aligned with the MAGA movement and was drawn to the vice president's frequent references to the Christian faith.
"I wasn't real sure about him at first, you know, like he's inexperienced, but I've seen everything he's done," Empson told Reuters.
"He's a real, genuine person, and he's also willing to proclaim his faith in Jesus Christ in public."
At last year's CPAC meeting in Oxon Hill, Maryland, Vance led the straw poll with 61 per cent of the vote, followed by Steve Bannon, a conservative podcaster and Trump adviser during his first term, at 12 per cent, and Florida Governor Ron DeSantis at seven per cent.
Rubio, who captured just three per cent of the vote last year, has risen in prominence as he plays a visible role in high-stakes foreign policy, including work related to the administration's actions in Venezuela and Iran.
No other contender in the poll other than Vance or Rubio received more than two per cent of the vote.
Several CPAC attendees told Reuters they would like to see Vance and Rubio on the ticket together.
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