Zackory Kirk, an influencer based in Atlanta who goes by the name The Zactivist and has more than 220,000 followers on Instagram, TikTok and other platforms, has been churning out mostly progressive content for more than four years.

It was only in the final stretch of the 2024 election that any real paid opportunities for him emerged from Democrats seeking to boost support for Vice President Kamala Harris, down-ballot candidates and issues such as reproductive justice. Nearly all the money Mr. Kirk made — and it wasn’t that much, he added — came in the nine weeks between Labor Day and Election Day.

“Up until the end, everything was pretty much free work,” he said.

And since Ms. Harris lost?

“Nothing.”

Now Democrats are facing a reckoning, not just over Ms. Harris’s loss to President-elect Donald J. Trump but also over how the left got so badly outflanked online. The sponsorship spigot that many influencers say was turned on too late is now running dry. And the content creators who embraced Ms. Harris fear falling even farther behind their Republican rivals, one viral TikTok at a time.

Interviews with more than a dozen Democratic content creators reveal a pervasive belief that Republicans have helped incubate a highly organized and well-funded ecosystem of influencers, podcast hosts and other online personalities who successfully amplified and spread pro-Trump content. And the content creators are blaming scattershot and underfunded efforts by Democrats to make an impression in a sphere they said the party as a whole had overlooked for at least a decade.