AIPAC, the main pro-Israel lobby on Capitol Hill, broke with its allies in the Republican Party, and came out against holding a vote on a new Iran sanctions bill until there is clear bipartisan support, The Hill reports.Here’s a crash course on the last few months of Israel-Iran-America politico-drama:1. In November, Western nations, plus Russia and China, granted Iran about $7 billion in sanctions relief in return for Iranian promises to slow down and limit its uranium enrichment. Supporters of the agreement argued that diplomacy should be tried before war. Opponents said that this agreement makes a war more likely and backs Israel into a corner.2. This drew the ire of Israeli Prime Minister Benjamin Netanyahu.3. AIPAC initially called for a bill in Congress that would reimpose the relaxed Iranian sanctions if Iran reneged on the deal or if it didn’t extend after the six month sunset.4. A bill authored by Sen. Robert Menendez (D-N.J.) quickly gained steam in the Senate, with most Republicans and many Democrats co-sponsoring it. Supporters said it would strengthen America’s hand at the bargaining table since it would punish Iran if it reneged. Opponents said that Iran would back out of the deal if it were threatened with punishments if it backed out of the deal.5. Pres. Obama threatened to veto an Iran sanctions bill that passed the Senate and House. To override a veto, both the Senate and House would have to support the bill with a two-thirds majority, which would not happen in this case, even though these negotiations have significant implications for Israel’s national security—something that Shmuel Rosner thinks the Israeli government has to take to heart.6. Senate Majority Leader Harry Reid (D-Nev.) has declined to bring Menendez’s bill to a vote, effectively preventing it from potentially becoming law.7. Thursday, Menendez spoke on the Senate floor, reemphasizing his support for the bill, even in light of Obama’s veto threat, but taking his foot off the pedal, cautioning that bringing his bill to a vote now would turn what is normally a bipartisan issue into a partisan one (Author’s note: Sorry, Senator, it already is partisan.)8. AIPAC, in an about-face, endorsed Menendez’s caution, effectively calling on lawmakers to wait to bring the issue to a vote until it has clear bipartisan support (i.e. enough support to override an Obama veto). The statement reads, in full:AIPAC commends Foreign Relations Committee Chairman Robert Menendez (D-N.J.) for his strong and eloquent statement on the Senate floor today outlining the threat of Iran’s nuclear program and the imperative of dismantling it. We appreciate his commitment to ensure that any agreement with Iran “is verifiable, effective, and prevents them from ever developing even one nuclear weapon.”We applaud Senator Menendez’s determined leadership on this issue and his authorship with Senator Mark Kirk (R-IL) of the Nuclear Weapon Free Iran Act. We agree with the Chairman that stopping the Iranian nuclear program should rest on bipartisan support and that there should not be a vote at this time on the measure. We remain committed to working with the Administration and the bipartisan leadership in Congress to ensure that the Iran nuclear program is dismantled.————-There are two reasons why AIPAC would change its mind. Either AIPAC is prepared to fight Obama on a veto and risk drawing the long-term ire of much of the Democratic Party (if it hasn’t done so already). Or AIPAC is not prepared to fight Obama on a veto and will oppose the legislation because it wants to maintain strong support in the Democratic Party (if it still has it). The former is more likely than the latter. Considering that until Thursday, AIPAC appeared ready to fight Obama on this issue, it probably calculated that there’s no honor in pushing a sanctions bill that will be vetoed and go no further. Better to wait, AIPAC figures, until it can muster a two-thirds majority (which, again, won’t happen) or until the political calculus changes to the point where a simple majority would suffice (maybe 2016?).These represent major changes in Congress’s historically strong and bipartisan commitment to Israel’s security, as David Suissa points out in his Thursday column. It now appears that AIPAC senses that its support on the Hill has fallen to the point where it must act less hawkish on Israel than the majority of Republican senators.