HARRISBURG, Pa. -

Both third-party candidates who hoped to compete in Pennsylvania's gubernatorial race have given up, leaving Republican Gov. Tom Corbett and Democratic nominee Tom Wolf to compete one-on-one.

Green Party nominee Paul Glover and the Libertarian Party's Ken Krawchuk said they could not gather the nearly 17,000 petition signatures needed to qualify for the Nov. 4 ballot by Friday's deadline.

Glover blames his failed bid on the large number of signatures required, his campaign's low public profile and a lack of more money to pay signature gatherers.

Krawchuk said third-party candidates actually must raise many more than the minimum number of signatures as insurance against petition challenges.

Statewide major-party candidates need to gather only 2,000 signatures, but they have to then win the nomination in the primary election.