For Elise Hall, the invitation came in the form of a phone call. Will Weatherford got a letter. In T. W. Shannon’s case, it was an email.

If the modes of delivery differed, the message from the American Conservative Union meant the same thing to each candidate: a chance to hit the big time at CPAC.

At the Washington-area conservative gathering each year, the greatest share of attention typically goes to the presidential candidates-in-waiting — the senators and governors who walk the halls with small teams of aides and bodyguards, testing out the sales pitches they’ll use during GOP primary season.

(PHOTOS: CPAC 2014)

A well-received speech can bring a burst of positive attention from national activists, or earn a second look from skeptical conservatives eyeing the 2016 field.

To others at CPAC, a breakout performance can mean far, far more.

For state legislators or constitutional officers, underdog candidates and upstart primary challengers, CPAC is a rare opportunity to put otherwise little-known names on the national map.

The classic example is Marco Rubio, who was a long-shot contender in an open-seat U.S. Senate primary in November 2009 — when the ACU suddenly selected the former Florida House speaker to keynote its national conference early the following year. It was an enormous stamp of approval for a candidate who needed a break.

Each year since then, CPAC has offered a shortlist of ambitious conservatives across the country the opportunity to present themselves for consideration to thousands of the hardest of hard-core activists.

(WATCH: CPAC 2014 speeches)

In 2012, now-Sen. Ted Cruz — at the time an unelected attorney locked in a difficult primary — appeared on a panel with other insurgent candidates such as Richard Mourdock, the Indiana treasurer who defeated longtime Sen. Dick Lugar in that year’s Republican primary.

Last year, the ACU selected a group of “10 Under 40” young Republicans around the country worthy of wider notice.

“It was kind of my entree onto the national stage,” recalled Shannon, 36, who recently stepped down as Oklahoma House speaker to run for the U.S. Senate. The Republican said he could still feel the lingering benefits of being named to last year’s ACU hot list.

“I’ve had people donate and I have only a social media relationship with them, and that started at CPAC,” said Shannon, speaking by phone from Oklahoma ahead of a CPAC panel appearance Friday. “There’s no question that it creates an environment for you to tell your story, and we have such a good story to tell.”

(POLITICO's full coverage of CPAC 2014)

In other words: When Shannon announced in January that he would seek to succeed outgoing Republican Sen. Tom Coburn, he was already known to activist groups, potential contributors and a gang of media figures here in Washington. Under other circumstances, he might have lagged in that area behind his leading competitor for the Senate nomination: Rep. James Lankford, a member of the Republican leadership team in the U.S. House.

There are a few other, comparable opportunities throughout the year, such as the social conservative-oriented Values Voter Summit or the RedState Gathering.

In Washington, at least, the ACU conference — despite screwball features like the regular addresses by Donald Trump — has a cachet of its own.

Weatherford, 34, who currently leads the lower chamber of the Florida Legislature, called the conference an opportunity to “brag about what’s happening” in various state capitals around the country — and to connect with other young GOP leaders in the states, like “my buddy T. W. Shannon.”

The two men had already crossed paths before they spoke at the same CPAC event last year, but have become fast allies since then. Weatherford is supporting Shannon’s campaign in a competitive open-seat Senate primary.

“It is a bit of a coming-out party,” said Weatherford, who is busy with Florida’s legislative session and not attending the current CPAC. “It was a great chance to talk about the fact that there’s an opportunity to create what I call pockets of freedom around the country.”