Gary Johnson says he’s made the ballot in all 50 states and D.C.

Libertarian Party presidential nominee Gary Johnson says he’ll be on the ballot in all 50 states plus the District of Columbia, lending his campaign new legitimacy as he fights to get onto the stage for the presidential debates.

Mr. Johnson said he and running mate Bill Weld are now the only nationwide option for voters looking for an alternative to GOP nominee Donald Trump or Democratic candidate Hillary Clinton.

“Gaining ballot access in all 50 states and the District of Columbia is a monumental task, as evidenced by the fact that we will be the only ticket other than the Republicans and Democrats to do so,” Mr. Johnson said this week after Rhode Island became the final state to approve the Libertarian Party for its November ballot.

Other candidates offering themselves as alternatives to the two big parties aren’t faring as well.

Green Party nominee Jill Stein will appear on ballots in all but a handful of states — but that handful includes Nevada and North Carolina, two key battlegrounds.

And Evan McMullin, an independent conservative candidate who launched his campaign last month, is lagging far behind, having won a place on the ballot in just nine states to date: South Carolina, Virginia, Colorado, Iowa, Utah, Louisiana, Arkansas, Idaho and Minnesota.

Requirements for getting on the ballot differ, with some states requiring massive signature drives for nonmajor party candidates.

Nicholas Sarwark, who is chairman of the Libertarian National Committee, said getting on all 50 states plus the District of Columbia, which also has electoral votes, is a “big milestone.” Typically, the party comes close, but this is the first time in 20 years that the party’s nominee has been on the ballot nationwide.

“It’s pretty exciting,” he said. “This is going to be a decision point for the Commission on Presidential Debates.”

Mr. Sarwark said Mr. Johnson is now on the ballot in the same number of states and territories as the two “old party” candidates, and that recent polling has shown that anywhere between 54 percent and 76 percent of Americans want to see Mr. Johnson on the debate stage.

“If they decide to ignore the will of the American people, that’s a choice that they can make, and they can go the way of other parts of American culture that have become irrelevant,” he said.

Mr. Johnson’s campaign also took out a full-page ad in The New York Times this week asking the commission to include him in the Sept. 26 debate. He’s thus far fallen short of the 15 percent polling threshold that’s needed to qualify.

The commission has defended the 15 percent threshold, which has been used since 2000, saying it strikes a balance by featuring candidates who have a legitimate chance to win and not being overly inclusive.

Regardless, the ballot access news is a welcome development for Mr. Johnson, who gained some unwanted attention last week after he stumbled over a question about Aleppo, later saying he had a brain freeze upon hearing the name of the Syrian city being torn apart by that country’s civil war.

Even if Mr. Johnson fails to make the debate stage, his supporters still have the potential to influence the election’s ultimate outcome. Though the libertarian platform generally aligns more closely with Republicans than Democrats, polling has shown that Mr. Johnson could end up pulling away more support from Mrs. Clinton than Mr. Trump.

According to the latest NBC News/SurveyMonkey tracking poll, 39 percent of Johnson supporters would opt for Mrs. Clinton in a two-way race, compared to 35 percent who’d choose Mr. Trump. Other polling has shown Mr. Johnson making inroads among Hispanic and younger voters — two planks of President Obama’s coalition that Mrs. Clinton is still working to coalesce around her candidacy.

A Monmouth University Poll released Wednesday showed Mr. Trump with a narrow 2-point lead over Mrs. Clinton in Nevada, 44 percent to 42 percent, and Mr. Johnson at 8 percent, meaning Mr. Johnson’s supporters could ultimately help sway the outcome in such key battleground states.