Libertarian presidential candidate Gary Johnson's poll numbers are on the rise, worrying some Democratic strategists who thought Johnson would siphon votes from Trump and not Clinton.

But a battery of recent polls show that young voters, particularly Bernie or Bust-ers and #NeverTrump-ers in the Midwest, are fond of the former governor of New Mexico. He's fared well in important states like Nevada, Arizona, and Colorado. Politico reported that Clinton's campaign operatives are worried Johnson's success in those states could hand them over to Trump.

Bob Miller, Nevada’s last Democratic governor, told Politico that Clinton "definitely" needs to worry about Johnson’s popularity in the state: "There’s just every kind of opinion you can think of. [The] northeastern part of the state and other parts of rural Nevada have a libertarian element."

A Quinnipiac poll released this week shows Clinton defeats Trump in a national head-to-head matchup, leading by five points at 48 percent to 43 percent. When Johnson and Green Party candidate Jill Stein are in the mix, however, Clinton's lead shrinks to just two points. The Quinnipiac poll showed Johnson had 13 percent of the national vote in a four-way matchup. And Johnson's campaign announced Tuesday that the candidate would be on ballots in all 50 states on election day.

"With a majority of Americans wanting a choice other than Donald Trump or Hillary Clinton, today we now know for certain that on Election Day, every voter in America will have that alternative option," Johnson said in a statement released Tuesday.

The same poll also shows that 60 percent of Clinton voters--along with half of Trump supporters--want to see Johnson on the debate stage with the two major candidates on September 26, the first presidential debate of the election cycle. Ron Nielson of the Wall Street Journal wrote a column this week calling for Johnson to join Trump and Clinton on the debate stage, arguing the number of Americans who self-identify as independents is high enough to demand viable, third-party political representation.

Johnson and his running mate, former Massachusetts Gov. Bill Weld, would need to poll at 15 percent nationally to join Trump and Clinton in the debates.

The Quinnipiac poll called the election so far "a largely negative presidential campaign, where most Americans are voting against, rather than for, a candidate."