For better or worse, political candidates need two key TV skills to succeed — the speech and the soundbite. They have to speak in complete paragraphs and in bumper stickers. Master both, and you’ve got a shot.

This week’s Democratic presidential debate in Houston is especially important for two contenders: Sen. Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE (D-Mass.) and Pete Buttigieg Pete ButtigiegBillionaire who donated to Trump in 2016 donates to Biden The Hill's Morning Report - Sponsored by Facebook - GOP closes ranks to fill SCOTUS vacancy by November Buttigieg stands in as Pence for Harris's debate practice MORE (D-Ind.). How they perform will determine if they can make television work for them or against them over the long haul of a national campaign.

Not long ago, Buttigieg had the buzz and Warren was seen as something like a health food diet — good for you, but low on excitement. However, as the Democratic presidential campaign moved out of the town hall phase and into the debate phase, the script began to flip.

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Warren was dismissed early on by some as a “school marm” in love with lecturing, which emphasized her bona fides as a Harvard professor and a policy wonk more than her economically difficult upbringing in Oklahoma.

During town halls, Warren gave answers filled with detail and context, putting her government and academic experience effectively on display. But those attributes, while admired, also seemed to build a fence around her own potential. Voters don’t like lectures, and obvious displays of high-level smarts often creates a distance between candidates and the electorate.

Televised town halls appeared to do the opposite for Buttigieg. The South Bend mayor’s campaign looked as unlikely as it could get: obscure small-town politician, gay, married. But Buttigieg took up the Fox News town hall challenge and impressed. His appearances there, and on CNN and MSNBC, displayed a modest Midwest manner, plain-spoken style and approachable demeanor — all of which made him seem less, well, unusual. He was as smart as Warren, minus the scholarly veneer that can keep people at arm’s length.

Quickly, there was a Buttigieg Movement and, unlike Warren, he seemed poised to rise to the top tier of candidates as debate season began.

But that’s not what has happened, not so far.

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Somewhere along the way, Warren developed a talent for bumper stickers, while refining her ability to speak in paragraphs. Right from the start, in the first debate last July, she came out strong with one of the night’s best lines, a challenge to the centrists onstage with her: “I don’t understand why anybody goes to all the trouble of running for president of the United States just to talk about what we really can’t do and shouldn’t fight for.” It was a memorable encapsulation of the case for activism, the kind of moment that makes headlines and lifts you out of the crowd. In each of the first two debates, she dominated screen time. And, sure enough, her poll numbers quickly moved up.

Buttigieg was not sound-bite ready. The understated style that bolsters him in town halls hinders him on the debate stage. He hasn’t performed poorly — in the second debate, he had the third most airtime, after Warren and Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE (I-Vt.) — but he hasn’t had the breakthrough debate moment that a candidate needs to stand out. The energy around him has cooled.

Despite this, Buttigieg’s fundraising numbers remain impressive. One reason: the settings for many fundraisers resemble town halls — medium-sized groups of people eager to have a real discussion with a candidate who connects. That’s Buttigieg serving up his best self.

The challenge Buttigieg still has to overcome is translating that best-self into the bumper-sticker machine of a crowded debate event. We can all admit onstage sound bites may not be the best yardstick for judging the political field, but it’s the tool voters have been handed right now as they hunt for any and all evidence of a candidate’s strength and endurance.

In Houston, viewers will look to see if Warren can sustain the TV skills that have helped bring her to the upper polling echelon. For Buttigieg, they’ll need a sign he has what’s required to reignite a candidacy that, until recently, showed top-tier promise.

That may be giving one night on television too much power, but several candidates dropped out of the race once they didn’t make the September on-camera cut; it’s that important to a national campaign. After this month, just three more debates remain before the Iowa caucuses. Not much time is left to see if the Warren-Buttigieg television script can fit in one more rewrite.

NOTE: This post has been updated from the original to remove an inaccuracy.

Joe Ferullo is an award-winning media executive, producer and journalist and former executive vice president of programming for CBS Television Distribution. He was a news executive for NBC, a writer-producer for “Dateline NBC,” and worked for ABC News. Follow him on Twitter @ironworker1.