Citing unfair treatment from the Democratic party, Harvard professor Larry Lessig announced the end of his presidential campaign on Nov. 2. (YouTube/Lessig2016)

Harvard professor and government reform activist Larry Lessig announced the end of his quixotic presidential bid on Monday, pinning the blame on capricious debate rules that barred him from ever appearing onstage with better-known Democratic rivals.

"The party won't let me be a candidate," Lessig said in his final campaign video. "I can't ask people to support a campaign that I know can't get before the members of the Democratic Party."

Lessig, who initially promised to be a "referendum president" -- resigning after he signed a package of reforms to take money out of politics -- said that the party's debate decisions silenced him.

"Our only chance to make this issue central to the 2016 presidential election was to be in those debates," Lessig said. "But last week we learned that the Democratic Party has changed its rules for inclusion in the debate, and under the new rule, unless we can time travel, there's no way we can qualify."

Lessig's decision ended a campaign that began only two months earlier, on Sept. 2, after he secured more than $1 million in donation pledges from supporters. While he did not qualify for the only televised debate so far -- a CNN forum widely seen as a victory for former Secretary of State Hillary Clinton -- Lessig earned reams of free media. He published essays in Politico and The Atlantic about the evolving strategy of his campaign; he admitted on HBO's "Real Time" with Bill Maher that it had been "stupid" to pledge that he'd resign after the Citizens Equality Act became law.

Last month, Lessig told the Washington Post that the Democrats had been so unfair to him that he might have to run as an independent. "If the party won’t allow me to run as a Democrat," he said, "that creates a lot of pressure to think about a different way of running that would allow me to make this case to the American people." Asked today via email if he would mount an independent bid, he wrote that "nothing (legal) is ruled out."

In the video, Lessig did not broach the subject at all. He focused instead on how Aaron Swartz, a brilliant technologist and political reformer, convinced him to focus on "political corruption." Swartz committed suicide in 2013, after an excruciating legal battle over some scholarly documents he'd downloaded from MIT's computer network. Lessig threw himself fully into the political work, marching across New Hampshire with fellow reformers, launching the largely unsuccessful Mayday PAC to back pro-reform candidates, and then running for president.

"No doubt, a better candidate could have gone further," said Lessig, "though I doubt any candidate could have worked harder."