Early on in the 2024 presidential campaign, President Trump’s message is confronting a different landscape than in his previous runs. There will be few social media outlets to connect that message with voters, a fraction of the press coverage, and difficulty securing commercial airtime or ad space to reach the electorate.

In 2016, journalists hung on Mr. Trump’s every word the way Gilded Age dailies like the Sun once hung on those of another showman, P.T. Barnum of circus fame. Whether they loved him or hated him, they could not ignore him.

Citing analysis from the tracking firm mediaQuant, TheStreet.com in 2016 reported that Mr. Trump “received $5.6 billion throughout the entirety of his campaign” in free coverage, “more than Hillary Clinton, Bernie Sanders, Ted Cruz, Paul Ryan and Marco Rubio combined.”

In 2020, he wielded the power of incumbency, which meant everything he tweeted to his 89 million followers was news. Now he’s banned from social media except for his own Truth Social platform, where he has 4.56 million followers in a total audience that Forbes pegged at about 2 million active users in April.

That’s a pittance compared to the 3 billion on Facebook and more than half a billion on Twitter. While journalists will still watch his posts, they are now acting more like the gatekeepers of what’s newsworthy, denying him the ability to go over their heads with a direct line to voters.

This filter was on display for Mr. Trump’s presidential announcement on Tuesday. MSNBC ignored it, CNN cut away after his declaration, and Fox News Channel dumped out of it around the halfway point. None of the Big Three broadcast networks carried it.

According to the Poynter Report, major print outlets framed the speech in light of his impeachments, on-going legal troubles, and the January 6 riot. The Washington Post’s headline demonstrated the trend: “Trump, Who as President Fomented an Insurrection, Says He Is Running Again.”

Mr. Trump now has a track record, and putting him on screens no longer guarantees huge ratings and tons of clicks, as he has often stated. Mr. Trump can try to buy eyeballs, but that will require money, and his fortune has taken a hit, a drain that will continue now that the RNC says it can no longer foot his legal bills.

Big donors might have filled the void, but they’re steering clear. On Tuesday, CNBC ran a story headlined, “As Trump Announces 2024 White House Run, GOP Megadonors Back DeSantis, Youngkin, Other Republicans.”

The Financial Review reported the same trend on Thursday. “More Republican mega-donors,” they said, “including Blackstone founder Stephen Schwarzman, have refused to back Donald Trump’s bid to reclaim the U.S. presidency, saying it’s time for the party to move on.”

The Democratic speaker of the California assembly in the 1960s, Jesse Unruh, coined the phrase, “Money is the mother’s milk of politics,” a truism that leaves Mr. Trump staring at an empty saucer, mewling like a hungry kitten.

Even if he turns out to be able to afford airtime, networks may balk, as they did in 2017. “ABC, CBS and NBC have joined CNN,” the Associated Press reported then, “in refusing to air an advertisement that lists President Donald Trump’s accomplishments during his administration’s first 100 days while blaming the ‘fake news’ media for not reporting on them.”

Should networks and Big Tech decide to veto 2024 ads, that’s another door slammed shut, making it difficult for Mr. Trump to be the combative candidate who savaged “the swamp” to such great effect in the past. He will no longer be able to dominate the news cycle, ceding the field to other candidates.

Mr. Trump seeks to accomplish the feat of President Cleveland. The only American president to win non-consecutive terms, he did so having won the popular vote twice, whereas Mr. Trump has failed to do so on two tries, underscoring the need to coax more voters to his cause.

Yet to paraphrase the anti-war slogan: Suppose they gave a campaign and nobody came? There can’t be a repeat of the Cleveland comeback unless Mr. Trump can communicate a winning message with tools almost as limited as those available to his Gilded Age predecessor — a megaphone that’s been whittled down to a whisper.