A new Quinnipiac poll confirms what most pundits already believed: Ohio Ballot Issue 2 — a referendum on the state’s controversial anti-union bill — is headed for a decisive defeat on election day.

According to the poll, Ohio voters plan to reject Senate Bill 5 — the measure which would sharply limit collective bargaining rights for 350,000 public employees — by a 57 percent to 32 percent margin. Although polling on statewide referendums is notoriously unreliable (especially in years where no major election is also on the ballot to drive voter turnout), it is clear that a broad coalition of Ohioans oppose the bill.

“Except for Republicans, every demographic group wants to repeal Senate Bill 5,” [Quinnipiac’s Peter Brown] said: men and woman, blacks and whites, the college-educated and those with less education, even nonunion households along with union families.

The bill seems poised for defeat despite picking up some high profile support; on Wednesday, Mitt Romney announced that he is “110 percent” behind the bill after his Republican rivals criticized him for waffling on the issue.

S.B. 5’s defeat would be a painful blow to Ohio Governor John Kasich, who has expended a great deal of political capital supporting the measure. When asked if he had a back-up plan in case of the strong likelihood that S.B. 5 is defeated on election day, Kasich replied “I never think ahead.”

No wonder the Quinnipiac poll also showed that Kasich’s approval ratings have hit a new all-time low.