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Israeli Prime Minister Benjamin Netanyahu's decision to call elections means that in January, as in 2009, a U.S. president will be inaugurated shortly ahead of a new Israeli government. Most likely that government will again be headed by Netanyahu, who starts his campaign with a commanding lead in the polls. The question will be whether President Obama or Mitt Romney will be able to use the fresh mandates in Washington and Jerusalem to launch a badly needed "reset" in U.S.-Israeli relations.

Though the Obama administration has worked closely with Israel in many areas, the president and Netanyahu have made a mess of their personal relationship. Obama sought to publicly distance himself from Israel early in his term, and he erred in centering his push for Israeli-Palestinian negotiations on a secondary issue - Israeli settlement-building in the West Bank and Jerusalem. He has never visited Israel. Netanyahu, for his part, publicly lectured Obama during his last White House visit, openly pressured Obama last month to set "red lines" on Iran's nuclear program and made it relatively clear that he would welcome Romney's election.

Netanyahu's poor relations with Washington could cost him votes, particularly if Ehud Olmert, a centrist former prime minister, enters the race. But the incumbent will present himself to security-conscious Israelis as the best qualified to confront Iran. In a speech to the United Nations last month, Netanyahu suggested that Iran's uranium processing could reach a critical point and invite a military strike by Israel by next spring or summer. If he wins the election, he might feel freer to ignore U.S. objections to such unilateral action, as well as those of Israel's security establishment.

Romney has promised to eliminate the "daylight" between the U.S. and Israeli governments. But he, no less than Obama, will have to find a way to agree with Israel on a strategy for Iran that keeps with U.S., as well as Israeli, interests. Last week Romney told CNN's Wolf Blitzer that he shared Netanyahu's view that Iran should not be allowed to obtain the "capacity" to build a nuclear weapon - a stricter stance than Obama's vow to prevent Tehran from building a bomb. But Romney added that "we have a long way to go before military action may be necessary" - a judgment that is closer to Obama's than to the Israeli leader's.

Neither Obama nor Romney is likely to succeed in policy toward Iran, not to mention their shared goal of creating a Palestinian state, unless they can forge a trusting relationship with Israel's leader. Obama may hope that Netanyahu is unseated; perhaps Romney secretly shares that wish. But chances are that one of them will have to find a better way to do business with this prickly Israeli leader over the next four years than Obama has in his first term.