Conventional wisdom says that any old Democrat could beat Pennsylvania Gov. Tom Corbett (R) this year, given his damaged political brand and an electorate convinced the state is on the wrong track.

A poll conducted for a third-party advocacy group shortly before the Democratic primary, however, calls that thinking into question.

The survey of likely voters, obtained by The Inquirer, tested two potential candidates against Corbett.

It found Tom Wolf, the actual winner of the nomination, would start with a lead of 51 percent to 37 percent against Corbett, including voters who were leaning toward one candidate or the other.

Yet the candidate who began the year as the Democrats' front-runner, U.S. Rep. Allyson Schwartz of Montgomery County, would have entered the general election trailing Corbett by one percentage point: 42 percent for the governor, to 41 percent for Schwartz, according to the survey, which included leaners.

At the time, Republicans in the Corbett orbit said privately they believed Wolf would be their most formidable opponent because of his background as a businessman, and because, as a first time candidate, he had no record in political office to exploit.

The consensus was that Schwartz, with thousands of votes in the U.S. House and a role in shaping parts of the Affordable Care Act, would have been easy to tie to the unpopular President Obama. Her Philadelphia association and past as the operator of a women's health clinic where abortions were performed may have proved vulnerabilities, some in the GOP believed.

Conducted by Hart Research Associates in Washington, the poll did not ballot-test the other two candidates in the primary, state Treasurer Rob McCord and former state environmental secretary Katie McGinty, against Corbett.

Results were based on telephone interviews from May 9 through May 12 with 810 likely voters -- of whom 42 percent identified themselves as Democrats and 36 percent said they were Republicans. The findings were subject to a margin of sampling error of plus or minus about 3.5 percentage points.

In the May 20 primary, Wolf won with 58 percent of the vote, to 18 percent for Allyson Schwartz; 17 percent for McCord and 8 percent for McGinty. (Note: does not add up to 100% due to rounding)

As of Tuesday, Wolf holds an average lead of 11 percentage points, according to the Real Clear Politics poll aggregator.