Johnson, a former two-term Republican governor of New Mexico, told CNBC's "Squawk Box" he's not thinking in terms of which candidate he's going to help or hurt. "The idea here is to actually win."
In a three-way race against Trump and Clinton, Johnson would get 8.5 percent of the vote, according to the RealClearPolitics average of national polls. Taken together, those same polls show Clinton and Trump in practically a dead heat, with 39 percent and 38 percent support, respectively.
"The only way that a third party has a [chance] of winning is to be in the presidential debates," Johnson said.
By being considered in polls alongside Clinton and Trump, Johnson said he believes he can possibly reach the 15 percent national support threshold required by the Commission on Presidential Debates to be included.
"If I'm in the presidential debates and I'm representing 25 million people, the eventual winner is going to have to do more than just pay lip service to the things I'm saying. I'm going to be talking about smaller government [and] regulations that benefit all, not a few."
If elected, Johnson said he would abolish the IRS, while eliminating personal income and business taxes. He would replace the current structure with a federal consumption tax.
On his website, Johnson's tax overhaul is described as allowing "every American and every business to determine their tax burden by making their own spending decisions. Taxes on purchases for basic necessities would be 'prebated' [or refunded], with all other purchases taxed equally regardless of income, status or purpose."
In 2012, Johnson ran for president as a Republican before switching to Libertarian.
While fiscally conservative, Johnson told CNBC on Wednesday that he was forced from the Republican Party because he's liberal on social issues, including support for the pro-choice movement on abortion, marriage equality and legalizing marijuana.
"I always thought the Republican Party was about small government. I think Bill Weld and myself have delivered that in spades," Johnson said, referring to Weld, the ex-Massachusetts governor he's chosen as his vice presidential running mate.
"[But] Republicans have pushed out those who are socially liberal," Johnson said, adding he even shares some views with self-described democratic socialist and Clinton rival Bernie Sanders.
"There is a website isidewith.com — I'd love everyone in the country to go onto that website and take the political quiz, and then see who they pair up with politically," he said. "Outside [of] siding with myself, amazingly I side with Bernie Sanders."