Harvard Law professor Lawrence Lessig is ending his campaign for the presidency, citing revised rules that would have again kept him off next week's Democratic debate stage.

The campaign-finance reform crusader launched a bid in September after raising $1 million for his campaign in a month. His single issue — get big money out of politics and reform campaign spending.

But even his fundraising, which eclipsed some other candidates who did make last month's first debate, wasn't enough to get him on the stage. With former Virginia Sen. Jim Webb and former Rhode Island Gov. Lincoln Chafee dropping out, though, it seemed like there was hope.

In a video announcing his withdrawal, Lessig said getting onto the debate stage was always critical.

"I may be known in tiny corners of the tubes of the Internets," he said, "but I am not well-known to the American public generally. But last week, we learned that the Democratic Party has changed its rules for inclusion. Unless we can time travel, there is no way I can qualify."

Initially, to qualify for the Nov. 14 CBS News debate in Des Moines, candidates had to reach 1 percent in three polls during the six weeks prior to the debate. But now, Lessig said, that benchmark had to be reached earlier, at the beginning of October.

"Under this new rule, I am just shut out," Lessig said.

Though he wasn't well-known compared to other Democratic candidates, including former Secretary of State Hillary Clinton, Vermont Sen. Bernie Sanders and even former Maryland Gov. Martin O'Malley, Lessig did have his devoted followers. He was popular in Silicon Valley and in tech sectors, for example.

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