Sure they can, if Shillery carries the state by a large enough margin no force on Earth can save Kirk.
You overestimate them, they have lost before, they wanted Dan Hynes to beat Quinn in 2010, he didn’t. And it’s only an assumption that they prefer Kirk, I wouldn’t be so quick to assume that, they have a lot invested in this little witch.
But the Combine got their Governor in 2010 (Quinn) and 2014 (Rauner).