As speculation mounts on Trump's running mate, contenders pitch the base at CPAC

"I think it's wide open," one expert said. "Trump keeps his cards very close."

The annual Conservative Political Action Conference has long been a proving ground for would-be presidents, launching the political aspirations of heavyweights like Ronald Reagan and Donald Trump.

This year, all eyes were on who could be No. 2.

Former President Trump has handily dispatched nearly all of his 2024 primary rivals, with only former South Carolina Gov. Nikki Haley hanging on while trailing by yawning polling margins and losing by double digits in every state that's voted so far.

With the GOP nomination all but determined, speculation over Trump's potential running mate is skyrocketing in the party -- and many of the lead contenders gathered at CPAC at the same time in what was viewed by some political observers as a tryout of sorts.

"CPAC is an opportunity for the VP hopefuls to make their case to the MAGA base. At the end of the day, Trump will probably have an 'Apprentice'-like audition for the VP slot," said one senior GOP strategist in Trump's orbit, who asked not to be quoted by name to speak more freely. "CPAC is a good venue because it is the most MAGA of the base -- the true believers."

"I think it's wide open," this person added. "Trump keeps his cards very close."

Florida Rep. Byron Donalds, Arizona Senate candidate Kari Lake, South Dakota Gov. Kristi Noem, entrepreneur Vivek Ramaswamy, New York Rep. Elise Stefanik and Ohio Sen. JD Vance all spoke at the Gaylord National Resort & Convention Center, offering a chance to test different messages to Trump's most loyal enthusiasts and for the party to see how much their rhetoric resounds with the GOP base.

The schedule of participants was so packed that conservative activist Tom Fitton, the head of Judicial Watch, remarked right after Lake's speech: "It feels like I'm the only one here not running for vice president."

Donalds focused his speech largely on foreign policy, urging U.S. allies to invest more in shared defense and declaring, "Decide Joe Biden, which country matters more to you, the border of the United States or the border of Ukraine?"

Lake focused on the border, too, calling fentanyl a "weapon of mass destruction while praising Trump as "exactly the man we needed in 2015, and he's exactly the man we need today."

Noem touted populist policies implemented in her state as a blueprint for America, sparking applause by declaring, "I was the only governor in this country who never once closed a single business" during the COVID-19 pandemic.

Ramaswamy leaned into culture battles, warning of a "war between those of us who love the United States of America and our founding ideals and a fringe minority who hates this country and what we actually stand for."

Stefanik echoed Trump in warning that his enemies would "stop at nothing" to "steal this next election," a line that resounded with the crowd.

And Vance heaped praise on Trump while vilifying many lawmakers' eagerness to further aid Ukraine in fending off Russia's invasion rather than focusing more on domestic issues. "If the thing you care most about is a conflict 6,000 miles away, you should not be a leader in this country," he said.

The speeches also featured subtle snipes, including Noem wondering "why did all these other people and candidates get in the race," apparently referring to Ramaswamy and South Carolina Sen. Tim Scott, two former 2024 candidates who are now being floated as potential Trump running mates.

Still, one thing that united everyone who spoke was their admiration for Trump's time in office.

Before the conference was in full swing, another source in Trump's orbit, who likewise didn't want to be quoted by name to be candid, told ABC News that they expected as much.

"I think what you're going to see at CPAC is a number of people who are trying to impress upon the crowd that they are as MAGA as Trump, that they are the best person to be his running mate," this person said on Wednesday. "You've got a number of people who are going to come out and try and convince what is a very conservative crowd that their Trump bona fides are sufficient enough."

Underscoring the focus on the "veepstakes," CPAC added to its straw poll a question of who attendees want Trump to pick as his No. 2, the first time in at least a decade that was included in the well-known -- but unscientific -- survey.

The poll of 1,478 CPAC attendees showed a tie, with Noem and Ramaswamy knotted up at 15%, followed by former Democratic Rep. Tulsi Gabbard at 9%, Stefanik and Scott tied at 8%, Donalds at 7% and Lake at 6%.

Conversations with more than a dozen attendees reflected those results and showed an array of preferences, with many talking about their choices with adjectives like "tough" while others said they're remaining open to several of the floated names.

"I just think she's tough," said Pat Thomas, a retired hay farmer from North Myrtle Beach, South Carolina, explaining why she'd like Noem to run with Trump.

"I love Byron Donalds. He was just up on the stage. He'd be an excellent VP candidate. Throw my weight behind him," Thomas Siens, an economist from Fort Worth, Texas, said shortly after Donalds spoke to the crowd.

"I like Kristi Noem. I like Ramaswamy. JD Vance, some of the ones that I would like to see. But it's a big decision. I think there's a lot of really good options for them," said Mark Wehrum, a physician from Orlando, Florida.

"I think there's a lot of people who are auditioning," said Jonathan Grier, a physician from Altoona, Pennsylvania. "I think CPAC is a good barometer for who's who."

But at the end of the day, the pitch to be Trump's running mate has only one real audience: him. And there are still months to go before the GOP convention this summer, with the second source in Trump's orbit skeptical that CPAC could make or break any one person's chances for promotion this year.

"My guess is Donald Trump will not watch one speech at CPAC and will show up only to give his speech and then to leave," this person said.