Election deniers spent the weeks leading up to Election Day sounding the alarm online about the potential for widespread voter fraud that would taint the results — something that officials say has never occurred in modern elections. Former President Donald J. Trump claimed “massive CHEATING” in Philadelphia on Tuesday before the polls had even closed.

Then the results arrived, showing Mr. Trump with considerable strength. Voices that had spent years shouting about election integrity suddenly faded to a whisper.

“As soon as it started to look like Trump was going to win, the election denialism went very, very quiet,” said Welton Chang, a co-founder and the chief executive of Pyrra Technologies, a company that monitors fringe social networks.

The sudden hush of election deniers in the wake of Mr. Trump’s victory on Tuesday underscores the narrative’s longstanding purpose as a means for Mr. Trump to regain power and challenge election results, experts say. When denying the election’s outcome suddenly proved politically useless, the influencers and Trump allies seemed content to simply set it aside.

The false notion that the 2020 election was stolen lived beyond social media as well, powering a broad movement of “election integrity” activists. For the past four years many of them had dedicated themselves to “fixing” the voting system to prevent a future “steal” — signing on as poll watchers, election workers and even election board members.

During the voting on Tuesday, several of the movement’s figures spread posts online that suggested activists were finding evidence of problems.