It is a rule of thumb in democracies that lame duck leaders should steer clear of bold new initiatives and sharp turns of policy. They’re supposed to sit tight until their elected successors can settle in and take the wheel. A decent respect for the opinions of the electorate demands that the voters’ decisions be honored, including the decision to repudiate an incumbent. Ehud Olmert, Israel’s outgoing prime minister, broke that rule September 29. And rightly so.

Olmert had resigned from his post a week earlier, chased from office by persistent corruption charges. He then became a caretaker prime minister, required to stay on until a new chief executive is sworn in. And yet, just days after resigning, in a dramatic newspaper interview on the eve of Rosh Hashanah, Olmert announced a historic turn in Israeli foreign policy. He vowed to spend his remaining days on the job pursuing his newly declared objective.

Breaking with every past Israeli leader, Olmert declared that Israel must give up control of East Jerusalem, the Golan Heights and virtually the entire West Bank if it hopes to achieve peace with its neighbors. He insisted that Israel currently is as strong as it has ever been — militarily, economically, diplomatically — and can afford to take risks. Haggling endlessly over an extra hill here or an extra kilometer of strategic depth there does little for Israel’s security in an age of long-range missiles, he said. He warned that the current Palestinian leadership might very soon be replaced by something far more intractable if Palestinians aren’t shown concrete gains. And he warned that the alternative to sweeping concessions is continuing tension and likely war.

Predictably, Olmert’s remarks have touched off a furious debate in Israel. Critics on the left complain that he should have said these things years ago, before the peace process lost its momentum and popular backing. Critics on the right say he is speaking foolishness, because the Palestinians don’t really recognize Israel, whatever they may say, and that makes peace impossible. Withdrawing to the pre-1967 borders, as Olmert urges, would weaken Israel’s defenses. Besides, the critics say, beyond strategic considerations, giving up Israeli sovereignty in East Jerusalem would rip the heart out of Jewish nationhood.

In any case, the critics add, Olmert has no right to launch a controversial new policy while heading a caretaker government. By resigning, they say, he has lost his mandate to lead. All he can do is manage day to day until his replacement is named — whether through new elections or by negotiating a new governing coalition within the current Knesset.

But the critics are wrong. They’re wrong on facts, wrong on law and, most important, wrong on substance. Olmert hasn’t lost his mandate from the voters, because he didn’t lose an election. He was elected two years ago to a four-year term. Last month, with two years left to serve, he resigned on his own because mushrooming corruption investigations were undermining his ability to do the job. Under Israel’s current election law — a law enacted by a government led by Benjamin Netanyahu’s own Likud party — the removal of a prime minister does not remove the ruling party’s mandate and force new elections. The first response, by law, must be an attempt to form a new coalition within the existing Knesset. That’s what Tzipi Livni, the new leader of Olmert’s Kadima party, is trying to do right now. Until she or someone else takes office, Olmert remains prime minister, with a full legal and electoral mandate to govern.

Most important, Olmert was elected with a mandate to do just what he is doing now. He was the first Israeli prime minister elected to office on an explicit platform of trading land and Palestinian statehood for peace. True, he intended to achieve a peace agreement without going back to the 1967 borders or giving up East Jerusalem. Since then, he’s learned that it can’t done. His previous view was based on a decades-old illusion, as he admitted in his newspaper interview. He shared that illusion, he said, and he was wrong.

Not that the truth was a secret. At least four Israeli-Palestinian model peace agreements have been hammered out over the past 20 years, from the controversial 1988 Amirav-Husseini agreement to the semi-official 1995 Beilin-Abu Mazen agreement, the official Camp David-Taba talks in 2000 and the unofficial Geneva Initiative in 2002. The outcomes have all been pretty much the same. There was never a realistic possibility of achieving anything different. Olmert is simply the first Israeli leader to admit it out loud. That’s partly because he is, despite his reputation, a man of principle. Partly, too, it’s because he is that rare politician who no longer needs to worry about losing an election.

Olmert probably won’t be able to conclude a deal in his final weeks in office, but he has left an important legacy: clarity. It’s been clear for a long time that peace would require, as Ariel Sharon often said, painful choices. Now we know what those choices are. Israelis must now decide whether they’re willing to go that extra mile for peace, or whether they would rather hold out for the whole pot — and sacrifice another generation to war.