In his second term, Richard Nixon had Watergate, but also the rescue of Israel in the Yom Kippur War.
In his second term, Ronald Reagan had Iran-Contra, but also a treaty eliminating U.S. and Soviet missiles in Europe, his "tear-down-this-wall" moment in Berlin and his lead role in ending the Cold War.
In his second term, Bill Clinton had Monica, but also came close to a peace treaty between Ehud Barak and Yasser Arafat.
Obama's second-term scandals -- IRS, Benghazi, wiretapping The Associated Press and Fox -- are in the low-kiloton range compared to the resignation of Nixon or the impeachment of Clinton.
And as Obama is going to get nada from a Republican House on guns, amnesty, cap-and-trade or a second stimulus, he should look for his legacy -- as Nixon, Reagan and Clinton did -- to foreign policy.
Two opportunities beckon. First, the mirage -- a Middle East peace. Essential to any treaty, however, is a withdrawal of Israeli "settlers" from the West Bank, a sharing of Jerusalem, Palestinian acceptance of Israel as a "Jewish state" and Arab repudiation of the "right of return."
Good luck. Bibi Netanyahu, who calls Jerusalem our "eternal capital" and Judea and Samaria our ancient lands, is not going to divide Jerusalem or uproot Jewish settlers from the West Bank -- not when he opposed their removal from Gaza by Ariel Sharon.
Bibi will not do it, cannot, if he wants his Likudnik coalition to survive. And Obama lacks the clout in Congress or this capital city to force Bibi to do anything he does not wish to do.
Hence Obama's legacy hopes lie not in Israeli-Palestinian peace talks in Washington this week, but in what is happening in Iran -- the inauguration of the president who replaces Mahmoud Ahmadinejad.
Hasan Rouhani was elected with 51 percent of the vote by the constituency that voted against Ahmadinejad in 2009. His triumph was due to his endorsement by former presidents Ali Akbar Hashemi Rafsanjani and Mohammad Khatami. Both had been kept off the ballot by Ayatollah Khamenei.
Rouhani is a founding father of the Islamic Republic and was a close ally of Ayatollah Khomeini. But he was elected on a pledge to revive the economy, get sanctions lifted, and re-engage with the West.
He won on a promise of better times for the Iranian people and an end to Iran's isolation.
Yet the only way he can achieve these goals is to come to terms with Obama on Iran's nuclear program. And as he was once Iran's lead negotiator on that program, Rouhani knows exactly what is required.
Despite the decades of acrimony between us, the basic elements of a Washington-Tehran deal are there.
Iran wants its rights under the Non-Proliferation Treaty (NPT) -- to peaceful nuclear research and nuclear power -- recognized by the United States. And it wants U.S.-UN sanctions lifted.
The United States wants more than verbal assurances that Iran is not building a bomb. We need intrusive inspections of Iran's nuclear facilities to assure us that she is not building an atom bomb.
As Reagan said, trust but verify.
Yet this seems not beyond the realm of possibility.
Despite the hysteria about Iran's "mad dash" to an atom bomb, Tehran has never tested a bomb and never produced the 90-percent-enriched uranium needed for a bomb, and does not have sufficient 20-percent uranium to further enrich for a bomb test.
Netanyahu's initial prediction that Iran was "three to five" years away from a bomb came -- in 1992. Since then we have been getting monthly updates on the imminence of the Iranian bomb, but no bomb.
Moreover, Khamenei has declared nuclear weapons anti-Islamic, and U.S intelligence agencies have never retracted their declarations of 2007 and 2011 that Iran has made no decision to build a bomb.
Rouhani's political future, the continued allegiance of his Iranian followers who want to re-engage with the West and the world, hangs on whether he can get a deal on Iran's nuclear program and a lifting of sanctions. He knows this.
What Rouhani cannot do is surrender Iran's rights to nuclear power and research. On this his nation is united. But he may be able to give the West what it requires, intrusive inspections, to prove that what Iran claims to be true is true -- that it has no nuclear weapons program.
If we can get that, we should be able to get a deal, and America can lift her sanctions, their objective having been achieved.
That would be the crown jewel of Obama's second term.
Who would be against such a deal? Bibi and the War Party that wants Iran smashed, as we smashed Iraq, even if that means another trillion-dollar unnecessary war.
Obama can, however, defeat the War Party coalition. He should congratulate Rouhani on his inauguration, declare his readiness for direct talks with Tehran, and appoint as negotiators national security hawks who want no war with Iran, but no Iranian atom bomb either.
History beckons. Obama should seize the moment.