The Illinois gubernatorial election of 2006 occurred on November 7, 2006. The Governor of Illinois, DemocratRod Blagojevich, won re-election for a four-year term scheduled to have ended on January 10, 2011. However, Blagojevich was impeached and convicted in 2009. Many observers expected the race to be close, especially considering the polling, which has shown Governor Blagojevich had a high disapproval rating. However, the Republicans fared poorly in elections since 2002 due to scandals involving prior Governor George Ryan, as well as changing demographics in the state as a whole (see blue state).
On November 7, 2005, Topinka announced that she would not seek re-election as state treasurer — instead, she entered the gubernatorial primary, hoping to challenge Democratic Governor Rod Blagojevich. The Republican primary was deeply divisive; her tenure as Party Chairman destroyed her support from the conservative wing of her party, and it was feared that her pro-choice and positive gay rights positions would be detrimental to her standing with the same conservatives. In December she announced that she would join forces with DuPage County State's Attorney Joe Birkett as a candidate for Lieutenant Governor of Illinois.
In February 2006, the candidates for the Republican nomination for Illinois Governor began running their first TV ads for the March statewide primary election. Rival candidate Ron Gidwitz's advertisements, attacking Topinka, were rebuked in the same week by the Illinois Republican Party: "In an unprecedented action, the Illinois Republican Party has officially rebuked the Gidwitz campaign for this ad because the Party found that the ad violates the Party's "Code of Conduct," which was enacted to police proper conduct among Republican candidates."
Later in February, candidate Jim Oberweis, another rival for the Republican Gubernatorial nomination, started a series of attack ads for television markets, against Topinka, that were even more widely criticized, mostly for using "fake" headlines on the images of actual Illinois newspapers.  These ads, like Gidwitz's ads, also came under review by the Illinois Republican Party.  Because of the controversy generated, several television stations withdrew Oberweis's ads. 
The Green Party became an established political party statewide, according to Illinois state election law, when Rich Whitney received more than 5% of the total vote for Governor. This status provides the party with several new advantages, such as lower signature requirements for ballot access, primary elections, free access to additional voter data, the ability to elect precinct committeemen, run a partial slate of candidates at any jurisdictional level, and slate candidates without petitioning. The only other statewide established political parties are the Democratic and Republican parties. It is rare for a new political party to become established statewide in Illinois, the last to do so being the Solidarity Party in 1986 and the Progressive Party before that.