Republicans, for their part, accuse the companies of suppressing free speech by censoring conservative voices — above all former President Donald J. Trump, who was barred from Facebook and Twitter after the riot on Capitol Hill on Jan. 6 last year. With so little agreement about the problem, there is even less about a solution.

Whether Mr. Obama’s advocacy can sway the debate remains to be seen. While he has not sought to endorse a single solution or particular piece of legislation, he nonetheless hopes to appeal across the political spectrum for common ground.

“You’ve got to think about how things are going to be consumed through different partisan filtering but still make your true, authentic, best case about how you see the world and what the stakes are and why,” said Jason Goldman, a former Twitter, Blogger and Medium executive who served as the White House’s first chief digital officer under Mr. Obama and continues to advise him.

“There’s a potential reason to believe that a good path exists out of some of the messes that we’re in,” he added.

As an apostle of the dangers of disinformation, Mr. Obama might be an imperfect messenger. He was the first presidential candidate to ride the power of social media into office in 2008 but then, as president, did little to intervene when its darker side — propagating falsehoods, extremism, racism and violence — became apparent at home and abroad.

“I saw it sort of unfold — and that is the degree to which information, disinformation, misinformation was being weaponized,” Mr. Obama said in Chicago, expressing something close to regret. He added, “I think I underestimated the degree to which democracies were as vulnerable to it as they were, including ours.”

Mr. Obama, those close to him said, became fixated by disinformation after leaving office. He rehashed, as many others have, whether he had done enough to counter the information campaign ordered by Russia’s president, Vladimir V. Putin, to tilt the 2016 election against Hillary Rodham Clinton.