Gov. Chris Christie’s “bizarre behavior’’ in refusing to say he’ll support a possible GOP challenger to Gov. Cuomo next year could derail his chances to become president, state and national GOP insiders have told The Post.

“Christie already has a problem with many Republicans refusing to forgive him because of his embrace of [President] Obama and his socially liberal policies,’’ said a nationally prominent GOP operative. “But this bizarre behavior in suggesting he won’t help a Republican defeat a Democratic governor, and a Cuomo no less, could finish off his chances of becoming his party’s nominee for president in 2016,’’ the operative continued.

Cuomo claimed last week that Christie, the new head of the Republican Governors Association — an organization whose purpose is to elect GOP governors — had quickly called him to say The Post was wrong in reporting the New Jersey governor was ready to back Westchester County Executive Rob Astorino, should he become the Republican nominee for governor next year.

“I spoke to Gov. Christie this morning, who told me the exact opposite,’’ Cuomo contended in reference to last week’s “Inside Albany” column.

But Christie spokesman Colin Reed refused to confirm Cuomo’s claim, referring questions to Christie political consultant and longtime GOP operative Mike DuHaime, who likewise refused to comment.

Some close to Astorino said they would be dumbfounded by Cuomo’s claim, since not only is Christie responsible for trying to elect GOP governors, he’s also had longstanding friendly relations with Astorino.

Other Republicans, meanwhile, said they were surprised that Cuomo would disclose what presumably was a private personal phone call from Christie.

“Cuomo has put Christie in a really difficult position,’’ said a prominent GOP operative.

The Post’s report on Christie’s plan to back Astorino was based on sources close to Astorino who were familiar with an hourlong private meeting between Astorino and Christie held last month at the RGA’s annual meeting in Arizona.

After it was published, the report was described as accurate by state GOP Chairman Ed Cox, who attended the RGA gathering.

Democratic insiders say Cuomo and his political aides are engaged in an all-out effort to pressure Astorino not to run for governor next year.

“They’re trying to head off contributors to Astorino, spreading the word that he’s not going to run, trying to convince Republican money people that he doesn’t have a chance, and letting it be known that the governor won’t be happy with those who go with him,’’ said a source close to the state Democratic Committee.

Insiders say Cuomo, who polls show would easily defeat Astorino at this time, fears the popular county executive — who won a landslide re-election last month despite being a conservative in a county where Democrats outnumber Republicans 2-1 — would be a strong enough vote-getter who, even in defeat, could damage Cuomo’s chances to run for president.

GOP Chairman Cox, engaged in what has been a lonely struggle against Cuomo, will make public an 18-page “jobs agenda’’ Monday that calls for sharp cuts in income and business taxes, reduced state mandates on local governments in order to reduce property taxes, and a green-light for fracking for natural gas in the Southern Tier.

“Gov. Cuomo has referred to New York as the ‘tax capital’ of the United States and admitted that high taxes are the ‘number-one reason businesses leave New York.’ He is absolutely right,’’ the document begins.

Cox has been virtually alone among the state’s Republican leaders in criticizing Cuomo and in trying to outline a platform for a race against him next year.