When it comes to rating races, it has long been our practice not to move extremely vulnerable incumbents into the other party’s territory until well into the election cycle – generally around Labor Day. Even then, they rarely move further than Lean. There are lots of good reasons for this policy, most of which grew out of lessons learned the hard way.

Republican Gov. Bruce Rauner has held the dubious distinction of being the most vulnerable incumbent of the cycle, and despite much heckling, has been sitting in the Toss Up column. But, the race recently hit a tipping point that moves it into the Lean Democrat column.

There are lots of reasons not to jump the gun on what amounts to waving the white flag on an incumbent’s chances for re-election. Some of them include the power of incumbency, the competence of an opponent’s campaign, and the increasing unreliability of public polls. All three factors collided in 2016 when Republican U.S. Sen. Ron Johnson of Wisconsin was seeking re-election and former Democratic U.S. Sen. Russ Feingold, whom Johnson had defeated six years earlier, was running to avenge his loss. There were 56 general election polls in that race, and Johnson was only ahead in four of them. Given those statistics, Johnson was moved into the Lean Democratic column pretty early in 2016. But, 15 of the 56 surveys went into the field between October 15 and Election Day, and Johnson was (barely) ahead in three of them. Johnson won the contest, 50 percent to 47 percent for Feingold and 3 percent for a Libertarian candidate. Of course, it wasn’t until after the election when Democratic operatives shredded Feingold’s campaign, holding it up as an example of malpractice. We put Johnson back into the Toss Up column 10 days before the election and no amount of second-guessing will resolve the question of whether Johnson should ever have left the Toss Up column.

One factor guaranteed to hurt an incumbent locked in a close race is the presence of one or more third-party candidates on the ballot. Again in 2016, GOP incumbent U.S. Sen. Kelly Ayotte of New Hampshire lost her re-election bid to Democrat Maggie Hassan by just 1,017 votes. But, there were two other candidates on the ballot running to Ayotte’s right; they combined for 30,339 votes, costing Ayotte the election. There are similar stories from statewide races in Montana in 2006 where Libertarians cost Republicans elections, and multiple elections in New Mexico in which Green Party candidates undercut Democratic nominees. It is rare when third party and independent candidates are truly competitive. More often than not they simply serve as spoilers for one party or the other.

It is the presence of a Conservative Party candidate and a Libertarian on the ballot that has created the latest obstacle to re-election for Rauner, and is the tipping point that moves the race into the Lean Democrat column. Rauner has had a very difficult tenure. First, he is a Republican in a very blue state, and while he is relatively moderate, he hasn’t enjoyed the same levels of popularity and success that fellow GOP Govs. Charlie Baker of Massachusetts or Larry Hogan of Maryland have experienced. His job ratings have sunk under the weight of a long-running battle (and its aftermath) over the budget, and adversarial relationships with state House Speaker Mike Madigan and Chicago Mayor Rahm Emanuel, who have proven adept at robbing Rauner of victories.

One of Rauner’s great advantages in politics has been his personal wealth. He spent heavily to win the office in 2014 and seems prepared to do so again, but Democrats neutralized that advantage by nominating billionaire philanthropist J.B. Pritzker. Pritzker had a primary and invested $70 million to win 45 percent of the vote. In the second quarter, he spent just over $20 million compared to $7.8 million for Rauner. It will be interesting to see how much Rauner steps up his spending in the final weeks of the campaign.

Pritzker’s message is pretty simple: Rauner’s tenure has been a failure and the state is worse off than it was when he took office. Rauner’s message against Pritzker is more complicated. One part plays off the state’s reputation for political corruption by linking Pritzker to former Gov. Rod Blagojevich, who is currently serving a 14-year sentence on a host of corruption charges. The investigation into Blagojevich included wiretaps and those tapes contain phone conversations between Pritzker and the Governor. Republicans also link Pritzker to Madigan, who has been a thorn in Rauner’s side and who wields an unusual degree of power. Finally, Rauner attempts to paint Pritzker as someone who uses his influence to garner preferential treatment and further enrich himself. As an example, the Rauner campaign has aired television ads detailing how Pritzker secured a six-figure deduction in his property taxes by taking advantage of loopholes that no average taxpayer would have been able to use.

It would seem, though that voters are turning a deaf ear to Rauner’s arguments. There have been five polls released since the March primary. Pritzker has enjoyed leads of between nine and 18 points. While Johnson trailed Feingold in a vast majority of polls, his deficit was never as much as Rauner’s is against Pritzker. The most recent survey, a Victory Research poll (June 26-28 of 1,208 likely voters) had Pritzker leading with 45 percent, followed by Rauner with 30 percent, Conservative Party candidate Sam McCann with 5 percent and Libertarian Kash Jackson with 2 percent.

It’s entirely possible, even likely, that Rauner can close this gap with Pritzker, but McCann and Jackson will siphon off enough of the vote to prevent Rauner overtaking the Democrat. The Republican primary proved that conservatives are unhappy with Rauner, who eked out a 51-percent to 49-percent victory over state Rep. Jeanne Ives even though she spent a fraction of the millions the incumbent did. In truth, an inanimate object likely would have gotten 40 percent against an incumbent who rarely adheres to Republican orthodoxy and often opposes President Trump. Generally, the GOP nominee would be able to unify the base, but this doesn’t seem to be happening for Rauner. McCann, who is from central Illinois, was first elected to the state Senate in 2010 and won one of the most expensive legislative races that year. He is far from a perfect candidate: there are questions surrounding his construction companies. But, he reflects the kind of conservative who would rather have a Democrat in office than support a RINO. Even if McCann doesn’t grow his support beyond the 5 percent he got in the Victory Research poll, that is enough to damage Rauner’s chances. Again, Ayotte’s re-election bid provides a very current example of how this works.

With a move to the Lean Democrat column, this is another GOP-held seat that Democrats are poised to pick up. Race ratings are not static and, like Johnson, Rauner might find his way back to Toss Up, but he will need a lot of breaks and Pritzker will need to stumble for that to happen.