Doyle McManus Peace negotiations, a wise U.S. diplomat once said, are like riding a bicycle: No matter how slow you’re moving, it’s best to keep going – because if you try to stand still, you’ll fall. Secretary of State John F. Kerry is putting that principle to the test in his dogged work on three of the world’s most tangled problems: Iran’s nuclear program, Syria’s civil war and Israel’s conflict with the Palestinians. Kerry hasn’t quite arrived anywhere yet on any of the three, but he is at least keeping the bicycle upright. In the U.S. confrontation with Iran, it took negotiators until last weekend to nail down the details of the interim nuclear agreement that was announced to great fanfare on Nov. 24. The deal, which requires Iran to convert its most dangerous uranium into a form that can’t be used for weapons, still doesn’t go into effect until next week. But U.S. negotiators say the fact that the agreement could be reached bolsters their confidence that Iran is serious about the next stage: negotiating a more stringent long-term deal that reassures the world that its nuclear program isn’t a threat. “After 34 years of hostility, the fact that we have been able to sit down and have a sustained, civil conversation with Iran is nothing short of revolutionary,” said John Limbert, a diplomat who was one of the 52 American hostages in Iran a generation ago. “Yes, it could always collapse, but it hasn’t.” The most immediate threat to the nuclear negotiations doesn’t come from radical mullahs in Tehran. It comes from election-year politics in Congress, where both Republicans and Democrats are eager to pass legislation establishing new sanctions to be imposed on Iran if a long-term agreement isn’t reached. Kerry and other officials have begged Congress not to act, saying the threat of new sanctions could derail the negotiations; White House spokesman Jay Carney even warned that the bill would be the first step in “a march to war.” The chance of success is still highly uncertain, but the negotiations are rolling steadily forward. In the civil war in Syria, Kerry’s progress is harder to gauge. Through relentless jawboning, he has kept preparations on track for a peace conference to begin Jan. 22 in the Swiss city of Montreux. But the conference won’t produce much peace. Even U.S. officials concede that Syrian President Bashar Assad isn’t likely to negotiate his own exit. And the Syrian opposition, while too divided to present a united front, agrees on one thing: Assad must go. Some powerful rebel factions have said they won’t attend at all, fearing that the conference could strengthen Assad’s claim to legitimacy. So Kerry and others have downgraded their goals. The idea, Kerry said Monday, is “to begin … a process that we all understand will be difficult and take some time.” But this diplomatic bicycle looks pretty wobbly. Since President Obama stepped back from airstrikes, then suspended aid to the rebels because of factional fighting, the United States has little leverage. In the Israeli-Palestinian talks, Kerry’s progress is even more difficult to measure. When the secretary of State embarked on the first of his many missions to Jerusalem, his chances of success appeared nonexistent; neither Israeli Prime Minister Benjamin Netanyahu nor Palestinian Authority leader Mahmoud Abbas was enthusiastic about negotiations. But Kerry has succeeded in nudging Netanyahu into reaffirming that the Palestinians should have an independent state as the basis for a deal. And Palestinian negotiator Saeb Erekat has said he has begun to believe that an agreement is possible. We’ve been there before, of course. But, Erekat told reporters last month, “the difference this time is John Kerry.” The road to any agreement remains long and difficult. Kerry insists he has no illusions, but he sounds almost starry-eyed when he describes the potential payoff. “Imagine what peace would do … for future generations of Israeli and Palestinian citizens,” he said last month. “The possibilities are infinite.” It seems hardhearted to fault a secretary of State for throwing himself into the world’s most intractable problems. To be fair, Iran’s nuclear program couldn’t wait, the Syrian tragedy shouldn’t wait, and the Israeli-Palestinian issue deserves a solution too. But realists as well as cynics can be forgiven for asking whether Kerry’s relentless focus on the Middle East comes with costs as well as rewards. If the peace conference on Syria fails, will the clout of the United States and its chief diplomat suffer? If Kerry devotes months to fruitless diplomacy on the Israeli-Palestinian issue, will that rob time from other priorities, including the clashes between China and its neighbors and the largely unaddressed problems of climate change? When I put those questions to a Kerry aide, his response was blunt. “What’s the alternative?” he asked. Or, put another way: When riding a bicycle in a disorderly world, a little forward movement is better than none at all.