WASHINGTON (AP) ― Secretary of State John Kerry on Wednesday underlined the difficulty he will face in trying to chart a path toward Mideast peace, urging patience on the details of any two-state plan while stressing that Israel and the Palestinians might only have two years left for a deal.

He told the House Foreign Affairs Committee that he was committed to breaking a logjam that includes nearly no Israeli-Palestinian talks in the past four years and no solution in sight after more than six decades of conflict.

But Kerry, who visited Jerusalem and the West Bank last week, said he sensed a “seriousness of purpose” in his meetings with Israeli and Palestinian leaders. He said the objective now is translating that seriousness into quick action.

The former senator has put new attention on restarting the peace process after his predecessor, Hillary Rodham Clinton, did not. 

“I can guarantee you that I am committed to this because I believe the window for a two-state solution is shutting,” Kerry told lawmakers. “I think we have some period of time ― a year to year-and-a-half to two years, or it’s over.”

“Everybody I talk to in the region and all of the supporters globally who care ... want us to move forward on a peace effort,” he added. “They’re all worried about the timing here. So there’s an urgency to this, in my mind, and I intend on behalf of the president’s instructions to honor that urgency and see what we can do to move forward.”

Kerry didn’t spell out why he believes so little time is left for an agreement that would establish an independent Palestine alongside a Jewish state recognized by its neighbors.

But these factors are likely to only make peace more difficult in the coming years, including the growing numbers and political strength of Israel’s settlers.

On his trip to the region last week, Kerry sought to gauge whether Israeli and Palestinian leaders were ready to make the compromises needed for any serious peace process to be restarted. There has been little movement in recent years on questions such as final borders, security arrangements and the status of east Jerusalem, which both sides claim for their capitals.

Conscious of the failures of Democratic and Republican administrations past, Kerry has tried to avoid setting any benchmarks for progress or deadlines for steps such as the resumption of direct talks. He told lawmakers he would not lay out a “schedule or define the process, because we’re in the process of working that out with the critical parties.”

“We have to find an equation here where we can dispel these decades of distrust,” Kerry said. “We’re trying to undo years of failure. And I think one can. But it has got to go carefully, step by step.”

Speaking about Syria, Kerry indicated no changes coming in the Obama administration’s strategy of nonlethal assistance for rebels fighting Syrian President Bashar Assad’s government.

Kerry, who is meeting U.S. allies in Istanbul this weekend, noted that more countries are moving toward providing weapons but that the U.S. was among those which “have chosen a different path of providing different kinds of assistance.”

Several U.S. allies in Europe, notably Britain and France, are pushing for the European Union to amend its arms embargo against Syria to allow weapons transfers to the rebels. The embargo will lapse unless it is renewed or modified by May 30.

Diplomats who favor the change say no decision on actually supplying weapons to the rebels has been made but they argue that just revising the embargo to allow for the possibility will pressure Assad to step aside.

On Venezuela, Kerry refused to endorse the chosen presidential successor of the late Hugo Chavez as the winner of Sunday’s close election.

Kerry was asked whether he recognized President-elect Nicolas Maduro, but the secretary of state would not say yes or no. Kerry backed opposition candidate Henrique Capriles’ call for a recount.

Having just returned Monday from a 10-day trip that ended with meetings in Seoul, Beijing and Tokyo, Kerry said the administration was determined not to repeat old mistakes when it comes to dealing with nuclear-armed North Korea, whether that includes promising food aid or making confidence-building agreements that the North has regularly broken.

The goal of the U.S. and all its partners is denuclearization, he stressed. China, the country with the greatest influence on North Korea, is on board even if it remains wary of putting too much pressure on its neighbor out of fear it might collapse.

Kerry also told lawmakers that the administration is making progress in its effort to hold people accountable for the Sept. 11 assault on a U.S. diplomatic installation in Benghazi, Libya. Several suspects have been identified as culpable in the attack that killed U.S. Ambassador Chris Stevens and three other Americans, he said, and the U.S. is working through the evidence and making its case.

More than seven months after the attack, no one has been brought to justice.