Gary Johnson

Libertarian presidential candidate Gary Johnson speaks to supporters and delegates at the National Libertarian Party Convention, Friday, May 27, 2016, in Orlando, Fla.

(John Raoux | AP)

Donald Trump and Hillary Clinton may not be the only candidates at the next presidential debate.

All eyes are on the 2016 Republican National Convention this week, but Libertarian Party nominee Gary Johnson has gained in the latest CNN/ORC poll. In a four-way matchup between Trump, Clinton and Green Party candidate Jill Stein, Johnson is up four points to 13 percent compared to Clinton's 42 percent, Trump's 37 percent and Stein's 5 percent.

If Johnson, former governor of New Mexico, polls at least 15 percent in five national public opinion polls before the first presidential debate, he'll be eligible to appear on the stage with the Democratic and Republican nominees. A recent CBS/New York Times poll had Johnson at 12 percent, according to the Libertarian Republic.

The Los Angeles Times reports "The Price is Right" host Drew Carey, a registered Republican who identifies as Libertarian, is hosting a fundraiser for Johnson this Saturday.

"Our goal is to help Gary reach the magic 15 percent number in national polls, which will place him on the big debate stage with Donald and Hillary," an invitation says. "And if that occurs, then all bets are off on who our next president will be!"

Former Minnesota Gov. Jesse Ventura endorsed Johnson for the White House last week in an op-ed for CNBC.

"I like everything Gary Johnson has said so far. He's fiscally conservative and socially liberal - something neither Democrats nor Republicans can offer. He also has a solid plan for bringing our troops home and restoring our economy. And, like me, he's a firm believer that marijuana should be legal," Ventura wrote.

Johnson, described as "The Libertarians' Secret Weapon" by The New Yorker, told the magazine that he stopped getting high earlier this year to focus on the campaign.

"As President, I will not indulge in anything," Johnson vowed. "I don't think you want somebody answering the phone at two o'clock in the morning--that red phone--drunk, either. Better on the stoned side, but I don't want to make that judgment."

Johnson previously ran for president in 2012 on the Libertarian ticket, but received less than one percent of votes. He told the publication that he hopes his running mate William Weld, former governor of Massachusetts, will make him the first serious third-party presidential candidate since Ross Perot ran as an independent in 1992.

Perot won a spot in the presidential debates, receiving 19 percent of the votes against Bill Clinton and George H. W. Bush. Johnson hopes to do the same -- and more.

"If you're not in the debates, there's no way to win," Johnson told The New Yorker. "It's the Super Bowl of politics."