Hewlett-Packard CEO Meg Whitman, who was Chris Christie's national finance co-chair, and Brian Baker, a Republican operative connected to the Ricketts family, both spoke on the call, sources who were on the call told CNN.
It came on Super Tuesday, as Trump prepared to build on his lead -- and Republican loyalists increasingly fretted the prospect that Trump will run away with the nomination.
Packer, a veteran of Mitt Romney's 2012 campaign who launched Our Principles PAC, told CNN that "it concerns me" that Super Tuesday's results might not make her task any easier by knocking any Republicans out of the field.
But, she added, "if the worst-case scenario is we have to take it all the way to the convention, that's fine by me."
Still, it's not clear that establishment Republicans have settled on a single strategy to defeat Trump -- a reality Packer acknowledged.
"The question is, do people feel like that's best executed by giving to a campaign that they're invested in or another candidate's super PAC or our effort?" Packer said. "We're not particularly greedy about it coming to our effort, although we have had a lot of enthusiasm for our effort."
Packer argued that Trump has not faced a sustained negative advertising campaign. She pointed out that so far, of the $215 million spent on the air in the GOP race, only $9 million has been funneled into attack ads against Trump -- less than the $10 million Romney's campaign spent in a single week in a single state, Florida, to undercut Newt Gingrich in 2012.
"The reality is that there has been no sustained campaign against this guy until last Thursday," she said.
The new push comes after the group aired ads against Trump in Iowa, but couldn't raise money to continue after Trump's second-place finish there.
Packer's super PAC also ramped up its efforts this week by hiring ex-Jeb Bush campaign aide Tim Miller as its communications director.
The group is already on the air nationally with an ad that launched Tuesday blasting "Trump University." It's airing on CNN and Fox News, as well as more broadly in Florida, Illinois and Michigan -- three key states that vote later this month.
The attacks on Trump could sound like the 2012 hits on Romney's work at Bain Capital.
Previewing her line of attack against Trump, Packer said: "This guy isn't a conservative. He probably isn't even a Republican. He is a con man who is incredibly vulnerable in the general election once Democrats get their hands on him."