The reign of Venezuelan strongman Hugo Chavez faces its worst trouble in years. The normally fractured opposition has suddenly united behind one man, Henrique Capriles Radonski, in the Oct. 7 presidential election. Chavez has already responded with an assault that makes our “negative ads” look quaint — and worse is sure to come. Will the Obama administration have the sense to do the right thing?

At a rally Sunday (attended by an American buddy, Sean Penn), Chavez said of Capriles: “It doesn’t matter how many times you change your costume, low-life; your pig’s tail still shows behind you as well as your pig’s ears. You snore like a pig. Well, what am I saying? You are a pig. Don’t try and hide it.”

Chavez ally TV host Mario Silva last week “exposed” a 2000 “police report” in which Capriles, known as a lady-loving macho, was supposedly caught in a car having sex with a man.

Meanwhile, the Jewish world is in an uproar over a Venezuelan radio show, “The Enemy is Zionism,” in which Capriles was portrayed last week as an imperial-capitalist-bourgeois agent of, yes, Zionism.

As the name suggests, Capriles Radonski’s maternal grandparents are Jewish. He has often spoken emotionally of his mother’s family’s escape from Poland during the Holocaust. But he’s Catholic and sports a wooden cross around his neck.

Nor do allegations that Capriles is a “Zionist agent” hold up. The 39- year-old governor of the state of Miranda is a center-left politician who shows little interest in global affairs, focusing instead on undoing the local miseries Chavez has inflicted.

On Feb. 12, Capriles won the Democratic Unity Party primary with 60 percent of the vote amid unusually high turnout, 3.1 million voters — a strong sign that, after 13 years of misrule, the public’s desire to unseat Chavez is growing.

Capriles boasts “a good track record of good governance at the state of Miranda,” says the Foreign Policy Research Institute’s Vanessa Neumann (a Venezuelan New Yorker who has crossed Chavez so often in her writings she’s been warned not to return). “If we had a free and fair election, he’d beat Chavez.”

But everyone knows that’s a big if. For starters, the country’s electoral board will be controlled by the Chavez ally and new speaker of parliament, Diosdado Cabello, an old political foe of Capriles.

Everyone expects fraud. But if the October election looks blatantly stolen, Neumann says, people could flood the streets and the government would declare martial law.

One caveat: While Chavez claims that his Cuban doctors managed to cure his cancer, rumors abound that he remains very ill, including an apparent collapse after a speech last Sunday. But even if cancer incapacitates him, some ally (possibly Cabello) will likely continue his “Bolivarian revolution” by stealing the election.

And that “revolution” is aggressively anti-American. Last week, for example, Chavez countered Western pressure by sending oil to embattled Syrian President Bashar al-Assad.

The US Treasury Department recently imposed sanctions on Chavez’s new defense minister, Gen. Henry Rangel Silva, for his ties to the drug- trafficking FARC rebels of Colombia. Silva is also accused of helping the Iranian-backed terrorist group Hezbollah in its attempts to gain footholds across Latin America.

Yet the State Department is cautious about confronting Chavez. Yes, last month it finally expelled Venezuela’s consul general in Miami, Livia Acosta Noguera — but only after Univision broadcast a recording of Noguera (at the country’s embassy in Mexico) exploring with a local hacker ways to cyberattack America’s nuclear facilities.

With his regional (Peru, Nicaragua, Argentina, Nicaragua, Cuba, Bolivia) and global (Iran, Syria, Hezbollah) alliances, his meddling ways and oil money, Chavez long ago replaced the Castros as America’s most dangerous foe in the hemisphere. Washington should grab at any chance to unseat him — and none is better than a democratic election.

Perhaps the Obama administration is too frightened of looking like an interfering yanqui to influence a Latin election. But can’t we at least denounce Chavez’s anti-Semitic and homophobic smears? (Copyright 2012 NYP Holdings, Inc. 02/21/12)