Sources in both parties said last week that their tracking polls were showing a dip in support for Sen. Daniel Biss and a trending increase for Chris Kennedy in the Democratic primary race for governor.

That’s the most likely reason why billionaire J.B. Pritzker’s campaign began airing negative ads against Kennedy last week. Pritzker has been playing a fascinating game of “whack-a-mole” with his two opponents while Gov. Bruce Rauner has tried to make Pritzker’s task difficult.

OPINION

Pritzker started as an almost complete unknown, so he spent millions to become known. And, for a while, it worked splendidly because neither Biss nor Kennedy had the money to run any own ads against Pritzker, let alone on behalf of themselves.

Enter Republican Gov. Bruce Rauner. Rauner’s campaign has acted as sort of a Super PAC for Biss and Kennedy, doing their dirty work for them by spending a fortune on anti-Pritzker TV ads featuring audio recordings of Pritzker’s conversations with former Gov. Rod Blagojevich caught on FBI wiretaps.

Rauner’s idea isn’t to knock Pritzker totally out of the race. Instead, by all accounts he wants Pritzker to barely win an ugly primary and then turn to the general election as a bruised and bloodied candidate who could more easily be finished off. That’s still a tall order in today’s anti-Republican national environment, but it’s all Rauner has.

With Rauner’s ads constantly bashing their candidate, the Pritzker campaign’s worst fear is that one of its Democratic opponents will catch fire.

The undecideds in this race are undecided mainly because those voters don’t like Pritzker (primarily because of Rauner’s ads) but have yet to hear a convincing “ask” by either of the other two candidates. Pritzker’s immense wealth also grates against years of the Democratic Party’s anti-billionaire orthodoxy. And his attachment to the establishment headed by House Speaker Michael Madigan naturally gives people pause, including Democrats, who don’t like the guy, either.

No matter how many times Biss and Kennedy claimed that Pritzker was trying to force them out of the race, Team Pritzker has never wanted either candidate to drop out. The fear was that opposition voters would coalesce behind whoever remained against a wounded frontrunner.

Winning a one-on-one race requires 50 percent plus one vote. In a contested, multi-candidate primary, a damaged-by-Rauner billionaire can still win with 40 percent of the vote or even less. So, this means Pritzker’s opponents had to be prevented from gaining too much ground, but not fall so far back that one or the other could consolidate support and reach 40 percent to beat him.

Kennedy was starved of financial resources by putting out the word that contributing to him was a very big no-no to the Democratic and union powers that be in this state. The effort prevented Kennedy, with his well-known family name, from moving forward in the polls.

The unknown Biss had been a distant third for most of the campaign, but then zoomed up to second place ahead of Kennedy after airing TV ads in the Chicago area. So, Pritzker hit him with negative TV ads over his support of pension reform and other issues. The ads apparently pushed Biss back down.

That left an opening for Kennedy, who reportedly started moving up. The easiest attack on Kennedy would’ve been the Democrats’ praise of the Republican Rauner. “I think Bruce Rauner is trying to do what he thinks is best for the state of Illinois,” Kennedy said in January when asked by a reporter if the Rauner campaign was, indeed, acting like some sort of super PAC on behalf of Pritzker’s challengers.

Then again, if Kennedy was hit that hard, there’s a real danger he’d be completely disqualified in Democratic voters’ minds, which would leave an opening for Biss to start surging yet again. So, the Pritzker ad focused on tuition hikes at the University of Illinois while Kennedy was chairman of the board of trustees. Just tapping the brakes rather than slamming them.

Kennedy used his latest surge to raise over $600,000 in just a few days last week, his best fundraising week ever. But that’s pocket lint to Pritzker, who can always increase the pressure on those brakes.

Expect this back and forth to continue right up until election day. Rauner will attack, forcing Pritzker to spend even more on positive ads while making sure neither of his two major opponents don’t catch a sudden tailwind. I wouldn’t want to be on that campaign.

Rich Miller also publishes Capitol Fax, a daily political newsletter, and CapitolFax.com.