Envision this scenario: A Republican state senator from Downstate Illinois runs as a third party candidate – taking on a GOP governor whose party was split in a divisive primary.

State Sen. Sam McCann’s Conservative Party challenge against Gov. Bruce Rauner? Yes, but that also describes an Illinois race from years ago.

In 1912, state Sen. Frank Funk’s Progressive Party bid to unseat Republican Gov. Charles Deneen followed a similar plotline.

It’s been more than a century since a three-way race for Illinois governor was competitive.

It didn’t turn out well for Funk – or Deneen. They wound up splitting the Republican vote and paving the way for a Democrat — Chicago Mayor Edward Dunne — to win. Funk’s bid earned him 26.1 percent of the vote — a third place finish that was still a better showing than most third party runs.

“That’s a long time ago, but that’s the last time I would say there was a real three-way race,” said Brian Gaines, a University of Illinois politics professor. “On the whole, third parties have been footnotes in Illinois for quite a long time, more than 100 years.”

Democrats are clearly hoping for a similar outcome in November. Democratic gubernatorial nominee J.B. Pritzker welcomed McCann’s candidacy, and Rauner slammed it.

Whether McCann winds up pulling enough votes from Rauner to tip the race to Pritzker remains to be seen. But history is not on McCann’s side.

Even though more than 100 candidates have run under various third party banners, no third party candidate has ever been elected governor of Illinois.

In fact, less than one in 10 third party or independent candidates for governor in Illinois history have won at least five percent of the vote, according to University of Minnesota researcher Eric Ostermeier’s Smart Politics report. He found that there have been 106 third party candidates on Illinois gubernatorial ballots in all 51 cycles since statehood, and only 10 reached even a 5 percent vote threshold. The last one was Green Party candidate Rich Whitney in 2006, when he got 10.4 percent of the vote in race won by incumbent Democratic Gov. Rod Blagoejvich.

Illinois gubernatorial Green Party candidate Rich Whitney speaks at a news conference at the Illinois State Capitol in Springfield in this Sept. 25, 2006 file photo. (AP Photo/Seth Perlman)

Gaines called the chances for a Gov. McCann “very slim,” partially because of hurdles the Plainview Republican faces before he can even get on the ballot — Illinois laws make it particularly difficult.

Because McCann is running in a new party, he’ll need to collect 25,000 signatures, and the petition circulators must be people who were uninvolved in the primaries.

That excludes anyone who circulated petitions for state Rep. Jeanne Ives, the Wheaton Republican who challenged Rauner in the primary.

“It’s not easy to get the signatures, and they’ll probably be challenged. There have been candidates tossed off the ballot,” Gaines said. “If I had to guess today I’d say he’s going to be on the ballot, but it’s not a sure thing, if it turns out volunteers circulating the petitions also worked on a primary, if they worked for Ives.”

It’s not just the new Conservative Party that faces problems with ballot access.

Green Party secretary Geoffrey Cubbage said part of the reason his party doesn’t have a candidate for governor this year was the decision to pull together candidates for more local races, rather than waste the resources on circulating petitions for a gubernatorial nominee.

“You have to make some tough decisions as a third party,” Cubbage said. “The likelihood that you’re going to run a statewide candidate and also a strong slate of local candidates in the same year is small.”

Libertarian candidate for governor Kash Jackson. From Facebook.

Libertarian hopeful for governor Kash Jackson said he’s aiming for 50,000 signatures to overcome challenges to his petitions. The Antioch-based candidate said to do that he’s often on the road Downstate, where “many voters in each election cycle feel as if they’re left out.”

Perhaps the most famous modern day third party run was launched in 1986 by Democratic gubernatorial nominee Adlai Stevenson III. In his second run for governor, Stevenson relinquished the party nomination, after candidates alligned with extremist presidential hopeful Lyndon LaRouche won the Democratic nominations for lieutenant goverrnor and secretary of state in the primary.

Back then, candidates for governor and lieutenant governor ran separately in the primary, and Stevenson’s chosen running mate lost.

Stevenson refused to run with Mark Fairchild, who won the Democratic nomination for lieutenant governor, or Janice Hart, who won the party’s nomination for secretary of state. After her upset victory, Hart famously declared “I’m going to revive the spirit of Abraham Lincoln and Gen. Patton, and we’re going to roll our tanks down State Street.”

Adlai E.Stevenson, caught in a weary moment at his Chicago election headquarters during his 1982 campaign. Sun-Times File Photo.

Stevenson bolted and created a one-time Solidarity Party slate. That meant no Democratic candidate for governor was on the ballot to run with Fairchild, who supported LaRouche.

“In some respects that wasn’t a real third party. That was the Democratic Party having goofed and lost control of the ballot and having to run with a different name,” the University of lllinois’ Gaines said.

In that election, Republican Gov. Jim Thompson won his fourth term, getting 52.7 percent of the vote to Stevenson’s 40 percent.

Jacky Grimshaw, Harold Washington’s campaign manager, was loaned out to Stevenson during his third party run. She remembers the challenge of running an unusual third party campaign.

“The question is why shouldn’t you be voting for the Democrat or Republican, so it takes a lot of resources, you need to be able to educate people, to target where your potential voters are,” Grimshaw said. “You look at the tendency of voters to vote one way or another, where are there independent blocks of voters, or independent voters among the Democrats or Republicans.”

In Stevenson’s case, it helped to have the support of the Democratic establishment.

Chicago Northwestern Station, where Adlai Stevenson shaking hands for commuter votes in 1986. Sun-Times File Photo.

“Adlai Stevenson was a force, he was a known name in Democratic politics,” Grimshaw said. “He wasn’t as ignored as John Doe would have been running as a third party candidate.”

Ostermeier said most candidates who have had some success running third party had some kind of political pedigree behind them.

“And that is the first recipe to having any sort of success on the ballot box,” Ostermeier said. “The second, of course, would be a sort of tumultuous political environment where one of the parties has a sort of fracture.”

That was partially the case back in 1912. Deneen beat six rivals in the primary as the GOP was split over by the Progressive Movement. Deneen was actually in sync with many of the progressives’ governmental reforms and even backed their champion Theodore Roosevelt for president, wrote Robert P. Howard in “The Illinois Governors: Mostly Good and Competent.”

Gov. Charles S. Deneen, left, and Frank Funk, right. Library of Congress photos.

But when Roosevelt left the GOP to run under the progressive Bull Moose Party banner, Deneen stayed loyal to the GOP, and Illinois Progressives recruited Funk, a state senator from Bloomington, as their gubernatorial nominee. Deneen finished second, head of Funk, but behind Dunne, who wound up becoming the only Chicago mayor ever elected governor of Illinois.

Rauner only faced one primary opponent, but Ives gave him a run for his money. The governor won by just three percentage points. Some polls show Rauner is the most unpopular governor in the country running for re-election this year.

If reluctant supporters of Rauner peel away to vote for McCann, it could spell doom for Rauner on election day.

“In Illinois I wouldn’t quite characterize it quite as a Civil War, but you definitely have vocal opposition to Rauner,” Ostermeier said. “That sort of sets the table for someone who has these ties to the Republican Party as Senator McCann does to have some success in the general election.”