Observing Americas politics from Tehran must feel like sitting court-side at the U.S. Open: Your head pivots side to side as you cheer your favorite player, hoping hell win the next set.

And thats dangerous. Americas hyper-partisan politics hamper Washingtons ability to conduct a coherent foreign policy.

Last year, President Trump withdrew his predecessors big gift to the mullahs, known as the nuclear deal. Since then, Mr. Trump has been tightening the screws on Iran.

Last November, his administration announced sanctions on ­importers of Iranian oil  except eight countries, including India, China, and Turkey, deemed temporarily exempt. On Monday, however, the White House announced that, come May, those exemptions will end.

The goal is to cripple Irans ability to export oil, its most significant cash cow. We are going to zero, said Secretary of State Pompeo. How long we remain there, at zero, depends solely on the Islamic Republic of Irans senior leaders. Weve made our ­demands very clear to the ayatollah and his cronies.

Beyond shuttering the nuclear program, America wants to see an end to the Islamic Republics ­regional adventurism, worldwide terror networks, provocative missile tests, and human-rights violations at home.

Bottom line, Iran must renounce ambitions that harm America and our allies and interests  not to mention the Iranian people.

Putting the squeeze on oil ­exports, however, isnt without risks. The administration calculates that any resulting spike in oil prices will be offset by increased production from Saudi Arabia and the United Arab Emirates, Irans regional archenemies.

Americas own energetic oil-and-shale pumping will do the rest. Even so, with the mayhem in Venezuela and Libya, to name but two troubled oil producers, Irans absence could make a significant dent in energy markets  and no president wants to enter a reelection year with rising gasoline prices.

Politics aside, Mondays announcement is sound policy. Combined with this months designation of the Iranian Revolutionary Guard Corps as terrorists, its meant to raise the price of Irans ­nuclear intransigence and revolution-exporting misbehavior.

With its economy faltering, Tehran will be forced to make a do-or-die choice: Renegotiate the nuclear deal, this time with real curbs on its illicit programs, or face regime collapse.

The only problem for Mr. Trump: Democratic presidential candidates threaten, as soon as elected and in office, to zag right back to the old nuclear deal.

The president of Iran, Hassan Rouhani, and Foreign Minister Javad Zarif, then, may be making the right bet as they watch our domestic politics court-side. That bet: Just wait it out. Hip to American political whims, they can see favored players winning the next set  and then perhaps the whole match.

They hear top Democratic contenders Bernie Sanders, Elizabeth Warren, and Kamala Harris announce that, if elected, they would return to the Iran deal hook, line and sinker. Once Vice President Biden enters the race, he, too, is likely to call for resurrecting the deal that made the administration he served famous.

So the mullahs wonder: Why give up now? The clerics believe suffering Iranians will grin and bear the economic pain of ever-tighter sanctions. All Rouhani & Co. need to do is fend off Revolutionary Guard hotheads and convince the supreme leader that Senator Sanders, or someone like him, will deliver Iran from Mr. Trumps wrath.

By 2021, once the screws are loosened, the economy will bounce back, and the Death to America chants will gain fresh credibility, too.

After all, under its current terms, the nuclear deal allows Iran in the next decade to resume uranium enrichment with fast-spinning centrifuges and to employ other state-of- the-art nuclear techniques  which the Islamic Republic was permitted to keep researching while its nuclear program was supposedly put on ice.

No one should ever mistake Iranians for fools. They believe they can sit it out, and judging from our partisan politics, which once quaintly aspired to stop at the ­waters edge, they may be right.

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Twitter: @BennyAvni. From the New York Post.