After announcing his candidacy via video on Thursday, Joe Biden will take to the stage at a union rally in Pittsburgh on Monday.

There seems little doubt which media format the former vice president, a self-styled scrappy kid from Scranton, Pa., prefers. Yet Biden, like each of the 20 Democratic candidates vying to take on President Donald Trump, must maneuver through an ever-evolving political-communication landscape.

Most start with introductory videos, which are gaffe-proof, even for gaffe-prone presidential prospects like Biden.

"One of the virtues of video is that it gives you complete control over the message — no interruptions, no shouted questions," said Darrell M. West, director of governance studies at the Brookings Institution.

However, added West: "Videos don't have the same authenticity as a campaign rally. There's no audience, and so it's hard to generate the same type of reaction."

And Biden thrives on reaction. And interaction. Sometimes too much, as he addressed in a recent video acknowledging — but notably not apologizing for — making some women uncomfortable.

A doctored version of Biden's video went viral (belying the control the format offers) and was gleefully tweeted by Trump with the words: "WELCOME BACK JOE!"

Don't expect Biden to counter, however: The president's prolific tweeting isn't his style.

"People who try to get themselves into communications structures in which they are fundamentally uncomfortable make a big mistake," said Kathleen Hall Jamieson, director of the Annenberg Public Policy Center at the University of Pennsylvania. "Joe Biden is not going to be the Twitter candidate."

Rather than isolate him, minimizing social media might make him a man of the people. Even though Twitter often drives (and debases) politics in this country, only 22% of Americans use Twitter, according to a new Pew Research Center poll. Of those, just 10% account for 80% of all tweets, yet that sliver of the population may have helped wedge Democratic candidates leftward even if most voters remain in the middle.

"The general public is still moderate and centrist, but in a nomination battle the people who are going to vote in Democratic primaries are much more to the left than I think has been the case," said West. "We're going to see a widening of the political agenda in this campaign that's rather extraordinary."

An issues-intensive contest may be welcomed by many, if not most, voters. And certainly by some candidates, including Amy Klobuchar and Elizabeth Warren, who have emphasized policy over biography. (In Warren's case, in part because of the continuing controversy over her previous claim of American Indian heritage.)

But breaking through is tough. "One of the things that we underplay at this point in the political cycle is the issues substance that is available from the candidates, and the question is how do you communicate that outside a print form?" Jamieson said.

Warren is using interviews and town halls to signal substance as her "unique selling proposition," Jamieson said. But it may be a "disadvantage to her because you just can't get any traction doing that in a world in which attention spans are abbreviated and the press is focusing on little other than tactics."

The election "will be a battle for attention," said Joshua Scacco, an assistant professor at the University of South Florida whose research focuses on how emerging technologies influence U.S. politics. "Democrats will have to figure out whether or not they want to nominate the candidate who will compete on policy — and that will mean that that candidate will play on a different field than Donald Trump — or compete with Donald Trump on the same playing field, which is attention."

The "attention candidates" so far are Biden, Bernie Sanders and Pete Buttigieg, Scacco said, with the youthful Buttigieg using a tradition as old as the republic and as classic as a Norman Rockwell painting — the town hall — to become an unlikely contender.

The televised versions of town hall forums aren't just a force for Buttigieg, but for CNN, which featured five of them on Monday. And Fox has gotten into the act with a highly rated Sanders event, watched by an audience that evidently included the president, who recently referred to Trump-friendly Fox as "we" in a tweet.

More Democrats will soon decamp to Fox for similar solo events. But, collectively, Democrats will not debate on Fox after the party froze out the network because of its tight ties to Trump.

In between his video launch and union rally, Biden will hold a fundraiser to try to catch up with the impressive, immediate haul that candidates Kamala Harris, Beto O'Rourke and Sanders bagged in the wake of their announcements (support also surged for Buttigieg after the town hall and other breakthrough moments). But what those funds have traditionally been spent on — campaign commercials — seem to be waning in importance.

"TV ads are fading both in terms of how much money is being spent on them as well as their ability to affect voters," said West, who literally wrote the book ("Air Wars") on political commercials.

"The data tells us that the effect of a television advertisement is very short-lived," Scacco said.

Indeed, voters may be wising up to the wiles of campaign ads, and audiences are atomizing: The buzzworthy "Game of Thrones" isn't as mass as previous prime-time hits, and is commercial-free, to boot.

Scacco expects TV spending to spiral as the primaries and caucuses commence, but he added that free media for candidates who can capture attention may matter more, and that overall campaign expenditures may in fact drop.

Jamieson, author of 16 books including "Cyberwar: How Russian Hackers and Trolls Helped Elect a President," believes social media's "very potent messages shared inside like-minded communities" will be key to "mobilize and demobilize voters."

Whether Biden or any other candidate can captivate remains to be seen, but the race itself already is doing so. According to a Fox News poll released last week, in a rare bipartisan consensus in an electorate riven with divisions, 57% of 2016 Trump and Clinton voters are "extremely" interested in the race — a level "typically only seen in the last weeks before Election Day."

And that day — Nov. 3, 2020 — is still 18 months away.

John Rash is a Star Tribune editorial writer and columnist. The Rash Report can be heard at 8:10 a.m. Fridays on WCCO Radio, 830-AM. On Twitter: @rashreport.