Republican gubernatorial contender Rob Astorino, who has vowed to approve fracking in upstate New York state’s gas-rich Southern Tier, yesterday accepted an offer of a pre-election tour of the gas fields of Pennsylvania — and challenged Gov. Cuomo to do the same.

Astorino, the Westchester County executive, told The Post that he would get a firsthand look at gas-drilling operations right across from the New York border at the invitation of Cabot Oil and Gas Corp., the second-largest gas producer in Pennsylvania.

He’ll tour Cabot’s operations in Susquehanna County near Binghamton, NY, where Cabot has invested more than $3 billion in the past few years.

“It’s unconscionable for this governor to leave people suffering in this economy while we are blessed with natural resources under our feet,’’ said Astorino, who, like Cuomo, has never visited a gas-drilling site.

An official state report has estimated that fracking would bring tens of thousands of jobs and hundreds of millions in revenue to one of the poorest areas of upstate.

“We urge the governor to join us and witness firsthand what his decision is costing New Yorkers,’’ said Astorino spokeswoman Jessica Proud.

The invitation to visit Cabot’s operations and witness the controversial fracking process was extended to Astorino and Cuomo late last week by George Stark, Cabot’s director of external affairs.

It came in the wake of what appeared to be a promise by Cuomo to go on a tour offered by anti-fracking activists, who have repeatedly threatened the governor with political retaliation if he approves gas drilling.

Stark called such an “anti’s tour’’ a “worthless circus and propaganda effort.’’

Cuomo’s office did not respond to a request for comment on Cabot’s offer.

Earlier this year, The Post disclosed that Cuomo turned down several offers of industry tours of fracking operations in Pennsylvania and, in one case, had insulted a major energy-company president by failing to respond to a formal letter requesting a meeting on the gas-drilling issue.

“Gov. Andrew Cuomo: lawbreaker.”

No, it’s not a new Astorino campaign ad but the informed opinion of one of the state’s leading scholars on the New York Court of Appeals, Professor Vincent Bonventre of the Albany Law School, Cuomo’s alma mater.

“He is violating the law,’’ said Bonventre, taking note of Cuomo’s unexpected decision Friday to wait two more weeks before nominating a new Court of Appeals judge.

“It is accurate to say the governor has violated the law. He has disobeyed the law. He has not obeyed the judiciary law that provides he make the nomination between 15 and 30 days after the [nominating] commission submits the list of candidates to him,’’ Bonventre said.

Cuomo claimed the delay, which will give the state Senate time to come back after the election to consider his pick, was necessary to avoid a pre-election partisan confirmation battle.

It was also seen by court watchers as a strong indication that Cuomo will select, much to the chagrin of many Democrats, the only Republican on a list of contenders, current Court of Appeals Justice Victoria Graffeo, whose 14-year term is expiring.

The governor and his top aides are all broad smiles at the likelihood that Nassau County Executive Ed Mangano, a Republican and close ally of Senate GOP Leader Dean Skelos, is expected to endorse Cuomo for re-election, but many of Nassau’s own Democrats are anything but thrilled.

As Mangano and Cuomo openly acted like political allies at a recent “beach cleanup’’ event in Oyster Bay, several local Democrats who want to see Mangano thrown out of office seethed with anger.

“I saw several Democrats who have been working to help Cuomo’s re-election look like they were about to throw up,’’ a prominent Nassau Democrat told The Post.