Democratic presidential candidate Lawrence Lessig speaks at the New Hampshire Democratic Party State Convention in Manchester, N.H., on Sept. 19. (Brian Snyder/Reuters)

Even though he is running for president for all the right reasons, Lawrence Lessig won’t be at the Democratic presidential debate in Las Vegas. But what he’s asking prospective voters to do is all wrong. In fact, they shouldn’t cast a ballot for him because of it.

First, the admirable part of Lessig’s presidential quest. Like millions of Americans, the Harvard Law professor and campaign-finance advocate is horrified by the ungodly amounts of money flooding politics since the Supreme Court’s 2010 Citizens United decision. Rather than shake his fist in anger or scribble off an op-ed piece about the consequences of unlimited campaign cash, Lessig decided to run for president for the sole purpose of changing the law to get money out of politics.

“Until we find a way to fix the rigged system, none of the other things that people talk about doing are going to be possible,” Lessig said in an interview with The Post’s Phil Rucker before his announcement in August. “We have this fantasy politics right now where people are talking about all the wonderful things they’re going to do while we know these things can’t happen inside the rigged system.”

And to prove he means business, Lessig made an irresponsible pledge. He would resign the Oval Office once he signed his campaign-finance and government reform package into law. A noble move that argues for him to never be given serious consideration.

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Candidates who promise to vacate the Oval Office after the completion of one legislative task or after one term should not be entrusted with it. They are the lamest of ducks before even taking flight. Congress would frustrate them in the former and wait them out in the latter. But since Lessig would leave long before the end of a first term, his choice of vice president becomes his most important decision, no matter what he says or does on campaign finance reform.

Because of Lessig’s promised departure, he becomes an after-thought in his own campaign. His vice president’s views on all things not related to money in politics, not to mention the v.p. himself or herself, would eclipse the top of the ticket. Lessig’s seeming selflessness demands an unreasonable amount of trust from the voter. He would require us to trust his judgment in making the selection. And he would require us to trust that his selection — someone “who is really, clearly, strongly identified with the ideals of the Democratic Party right now,” he told Rucker — would follow through on whatever assurances were given to get the nod in the first place. That means, for the first time in history, folks would go to the polls to vote FOR a vice president.

When I vote for president, I’m voting for someone who wants the job and the awesome responsibility that goes with it. Someone who knows the presidency is not a single-issue domain. Someone who could tough it out for potentially eight years. Anyone who doesn’t meet that level of seriousness doesn’t deserve anyone’s  vote. Given Lessig’s standing in the polls right now, there is no danger we will have to worry about it.

Follow Jonathan on Twitter: @Capehartj