GOP strategists fear Trump has an unexpected secret weapon helping him in New Hampshire

Donald Trump’s most outspoken foe is becoming his biggest asset in New Hampshire and is threatening to become the key that lets the former president win the state, experts warn.

Chris Christie’s whole campaign has been devoted to laying into Trump, calling him a “dictator,” a “petulant child” and a “crazed lunatic.”

But, according to GOP strategists, his place in the race is now throwing his arch-enemy a gift by having a major splitting effect on the anti-Trump vote.

“Chris Christie is a monumental problem for Nikki Haley,” Mike Dennehy, a former Republican National committeeman from New Hampshire who claims to be neutral in the race, told Politico.

“They are both currently splitting the Independent vote, and Haley desperately needs those votes if she is to have a chance of knocking off Trump in New Hampshire.”

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Haley is now Trump’s closest competitor, according to several polls. Christie is running way behind. Polls also show that, of Christie’s supporters, 75 percent say they would have Haley as second choice.

“Christie definitely makes Haley’s math more challenging,” Jim Merrill, who headed up Sen. Mitt Romney (R-UT) and Sen. Marco Rubio’s (R-FL) past New Hampshire campaigns, told Politico.

“It’s safe to say that few Christie voters here would ever back Trump, so Haley would benefit if Christie withdrew.”

But Christie’s camp said nobody has asked him to drop out or form alliances, and that the former New Jersey governor has no intention of doing so — in fact, he’s about to launch a $3.5 million TV advertising campaign in the state.

“One former presidential candidate and one potential candidate called” Christie “within the last week [and] encouraged him to stay in the race,” his campaign told Politico.

The campaign didn't identify the callers.

“Many Christie voters now see Haley as just another enabler and excuser of Donald Trump and his worst actions, as if she’s really only angling to be his VP, not actually beat him,” Christie adviser Mike DuHaime told Politico.

“But here’s my problem. If I were to drop out and support Nikki Haley, I have no confidence — no confidence — in the fact that she’ll make the case against Trump,” Christie said at a recent campaign event.

“Not all of my voters are going to go to her, because a lot of the people who are voting for me are voting for me because I’ve had the guts to stand up to Trump.”