GOV. CORBETT, beset by poll numbers that show voters don't want him to win another term, finally got some good news yesterday.

Montgomery County Commissioner Bruce Castor has decided against challenging Corbett in a 2014 Republican primary.

Castor, via Facebook and Twitter, thanked his supporters but said such a "massive undertaking" would be impossible given his responsibilities to Montgomery County, to the law firm where he works and to his family.

Castor had been mulling a run since December, saying he would make a decision by the spring.

He cited three reasons:

* Corbett's role as state attorney general in the investigation of child sexual abuse by former Penn State assistant football coach Jerry Sandusky.

* Corbett's problems getting legislation through the state General Assembly.

* Corbett's inability to help his handpicked candidate win the post of attorney general last year.

- Chris Brennan