The annual South by Southwest (SXSW) conference in Austin, Texas, is known for launching cutting-edge tech companies like Twitter and Foursquare, and introducing new music and critically acclaimed films. In its 33-year tenure, the festival has also become a mecca for Democratic politicians seeking to appeal to left-leaning millennials in a key primary state.

As the 2020 presidential race kicks into gear, Democratic candidates are flocking to SXSW, hoping the festival will serve as a launchpad for their campaigns. Republicans, as well as former Starbucks CEO Howard Schultz, who is considering an independent bid for president, will also be there.

"The weekend appearances by a collection of Democrats, Republicans and independent Howard Schultz at what was once known as a modest music festival amounts to the largest gathering of declared or potential presidential candidates of the year," said CBS News political correspondent Ed O'Keefe.

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"Much of what is discussed this weekend could end up being fine-tuned for voters in the early primary states," he added.

Declared Democratic candidates Amy Klobuchar, Elizabeth Warren and Pete Buttigieg will speaking at the conference Saturday. Trump primary challenger Bill Weld, a Republican, is also speaking, as is Republican John Kasich, who is publicly mulling a 2020 primary bid.

Rising Democratic star Alexandria Ocasio-Cortez is also set to appear at the festival on Saturday. And on Sunday, Democratic candidates Jay Inslee, Julián Castro and John Hickenlooper are speaking.

Ed O'Keefe said the SXSW events are opportunities for presidential hopefuls.

"If there's anything a presidential candidate needs, it's to get in front of a crowd, whether it's an early primary state, or a potential swing state like Texas, so I think they see this as a real opportunity to come, road test some messages," he told CBS affiliate KEYE in Austin. It can also be a venue for boosting fundraising.

"There's money here for the Democrats to raise, and undoubtedly some of them when they're here will be meeting with people who may donate to them," O'Keefe said.

Although politicians like former President Obama and Sen. Bernie Sanders have appeared at the festival previously, more politicians will be at this year's festival than ever. After the 2018 midterm elections saw several new Democrats elected to the House of Representatives in Texas, and Democrat Beto O'Rourke only losing narrowly to Sen. Ted Cruz, Democrats are hopeful that the state is turning ever more blue.

"That the event is happening in Austin, the southern capital of liberalism and home to a burgeoning tech industry full of employees and executives wealthy enough to donate to political candidates, doesn't hurt and is part of the draw for contenders," O'Keefe said. "And polling in recent weeks here shows President Trump earning less than 50 percent approval, a poor showing for a Republican president that suggests Texas could be more susceptible to a stronger challenge by Democrats."

Schultz said in an interview with O'Keefe on Friday that he believed Texas is an important battleground for the upcoming presidential contest.

"Texas is a very important state, and for the first time maybe since 1976 it could be a state that a Republican president, Republican candidate may not win," Schultz said.