Pennsylvania Gov. Tom Corbett is far and away the most vulnerable incumbent of 2014, as a new poll from Pittsburgh’s Robert Morris University indicates.

The poll, conducted Aug. 18-22, showed Democratic challenger and businessman Tom Wolf with a 30.8 percentage-point lead over Republican Corbett among likely voters. It shows Wolf with 55.5 percent, and Corbett with 24.7 — in other words, the gap between the two candidates is even larger than Corbett's entire share of the vote.

The poll used an online survey instrument, has a 4.5 percent margin of error and sampled 500 residents, including 372 likely voters. Corbett did even worse among all 500, clocking in with just 20 percent of the vote.

The governor had a particularly weak showing among women and voters age 18-39. Respectively, just 12.2 and 12.8 percent of those groups said they would vote for him in November.

Corbett is the only incumbent Republican up for re-election this November — including members of the U.S. House, senators, and other governors — whose seat is listed as “likely Dem” on RealClearPolitics’ race ratings.

“While a sizable chunk of voters has yet to choose a candidate to support, there are not enough undecided voters to make the difference for Corbett,” said RMU political scientist Philip Harold in a press release.

If he’s right, then “vulnerable” may be too generous a designation.