Here comes Benjamin Netanyahu's speech to Congress

Israeli Prime Minister Benjamin Netanyahu is about to address a joint session of Congress on the dangers of a possibly impending nuclear deal with Iran, which reportedly involves a 10-15 year restraint on the Iranian nuclear program that would reportedly allow Tehran to operate as many as 6,500 uranium enrichment centrifuges.

The speech (11 a.m. EST) was arranged on the initiative of House Speaker John Boehner. It was not authorized by the executive branch and has already harmed relations between the US and Israel.

The administration is scaling back the information it shares with Israel about the Iran negotiations. President Barack Obama, Vice President Joe Biden, and 56 out of 188 congressional democrats will not be attending the speech. Neither will Secretary of State John Kerry, who will be meeting with Iranian foreign minister Javad Zarif in Montreux, Switzerland instead.

Whatever Netanyahu actually says, the purpose of his speech is to build up congressional opposition to the coming deal.

Congress cannot stop a deal on its own, since the accord will be structured as a series of nonbinding political agreements precisely in order to circumvent any constitutional need for US congressional consent. But it can impact a nuclear agreement in other ways.

Congress could refuse to lift the sanctions on Iran that it passed, forcing Obama to affect a deal through a series of executive waivers - and raising the possibility that a future president would simply decide to stop issuing those waivers and re-impose sanctions.

As former US ambassador to Iraq and Washington Institute for Near East Policy scholar James Jeffrey argued, Congress could also strengthen the deal by providing "advance authorization for the administration to use force if Iran races to a weapons capability."

And Jeffrey notes that strategic concert with Iran is also a broader diplomatic project than Obama could possibly implement during his remaining years in office (Jeffrey argues that detente with China actually took decades to implement). Both the current Congress and a future presidential administration could have a role to play in firming up a deal while undercutting Iran's strategic ambitions.

Even if Congress can't cancel out or scuttle a deal, Netanyahu can at least make the case for damage control - and demonstrate that most of the US Congress and even most of the members of Congress from the president's own party are at least willing to hear him out.

The big question is what kind of approach Netanyahu will take.

In his speech to the American Israel Public Affairs Committee on March 2nd, the Israeli prime minister referred vaguely to disagreements on Iran policy and didn't go after Obama or any of his initiatives specifically. The Iran standoff was framed as a family spat no different from past rifts between the US and Israel.

Will that kind of non-confrontational approach cut it for such a risky speech on Netanyahu's signature issue?

If he decides the answer is "no," the prime minister could expose privileged information about the US negotiating position - something the US administration has specifically warned him against doing. He could also directly endorse pieces of Congressional legislation, like a proposed bipartisan bill that would impose additional sanctions if the negotiations with Iran collapse or if Iran violates its nuclear commitments - a bill that Obama has repeatedly promised to veto.

Netanyahu could give a conciliatory speech emphasizing the US and Israel's shared interests and attempting to reign in damage to the US-Israel relationship that the speaking gig may have created. Or he could give a no-holds barred account of exactly where the US and Israel differ and suggest a legislative prescription.

He has been Israel's prime minister for nine years, evidence of incredible political acumen given the country's fractious politics. But Netanyahu clearly believes that the Iran nuclear issue transcends mere politics - a conviction that could lead to a speech that actaully delivers on the months of controversy it's generated.