WASHINGTON (AP): Barack Obama, winding up the Middle East segment of an international tour, sought to reassure Israelis _ and, by extension, American Jews _ that his willingness to deal directly with Iran was a strategy to chart a new course in American diplomacy, not a sign of weakness.

The first-term Illinois senator also promised the Israeli and Palestinian leaders he met with Wednesday that he would use the power of the White House, if he is elected, to try to resolve their decades-old conflict.

In his public remarks in an Israeli city frequently hit by Palestinian militant rockets, Obama sidestepped a question of whether he would condone an Israeli attack to prevent Iran from obtaining a nuclear weapon. But he said several private meetings with Israeli politicians had not left the impression that he would be ``pressuring them to accept any kinds of concessions that would put their security at stake.''

Obama's trip, which also brought him to Afghanistan and Iraq, and will end with stops in Europe, has allowed the candidate to spotlight his policies on the international stage in an effort his campaign hopes will show Americans that his message of change resounds outside U.S. borders.

Meanwhile, his Republican rival, John McCain, was in the U.S., appearing in supermarkets and other less exotic locales in campaign stops where he occasionally found himself on the defensive on issues he maintains he is more qualified than Obama _ foreign and military policies.

In a stop in Bethlehem, Pennsylvania, McCain found himself pushing back against Democratic criticism that he misstated when the troop buildup ordered by President George W. Bush began, saying elements were put in place before Bush announced the strategy in early 2007.

Obama's contends that a Sunni revolt against al-Qaida combined with the dispatch of thousands more U.S. combat troops to Iraq produced the improved security situation there. McCain called that a ``false depiction'' and said the Sunni revolt was made possible by the surge.

McCain argues that the troop ``surge'' was gradual and ``made up of a number of components,'' some of which began before the arrival of 30,000 additional troops.

Iran has been of increasing concern in the Arab world and in Israel because of its apparent efforts to acquire nuclear weapons. Israel last month sent warplanes over the eastern Mediterranean for a large military exercise that U.S. officials described as a possible rehearsal for a strike on Iran's atomic project.

Obama on Wednesday professed ``an unshakable commitment to the security'' of Israel, whether the threat comes from terrorists, Iran or elsewhere.

He also stressed that he would use ``big sticks and carrots'' to persuade Iran not to develop nuclear weapons.

Obama has repeatedly been criticized as naive by McCain for saying he would be willing to talk directly with U.S. foes like Iran. But Obama said the goal for such diplomacy was ``not because I'm naive about the nature of any of these regimes.''

``It is because if we show ourselves willing to talk and to offer carrots and sticks in order to deal with these pressing problems, and if Iran then rejects any overtures of that sort, it puts us in a stronger position to mobilize the international community to ratchet up the pressure on Iran,'' Obama said.

The comments drew a quick response from McCain's campaign, which accused Obama of backtracking on his expressed willingness to meet with Iran's leaders without preconditions. Obama said he had not changed his stance.

McCain on Wednesday focused on domestic issues.

The cost of oil and gasoline is ``on everybody's mind in this room,'' McCain told a town-hall meeting in Wilkes-Barre, Pennsylvania.

Citing Americans' deepening worries about the economy, he credited the recent $10-a-barrel drop in the price of oil to Bush's recent lifting of a presidential ban on offshore drilling, an action he has been advocating in his campaign.

He also criticized Obama for opposing drilling on the Outer Continental Shelf. In lifting the offshore drilling ban, Bush urged Congress to follow suit and arguing that the psychology of lifting the ban has affected world markets.

An Associated Press-Ipsos poll released Wednesday showed that the economy is the nation's top concern. Anxiety about energy has grown more since spring than any other issue, while the focus on Iraq continues to fade.

Forty-four percent said the economy was the country's most important problem, an increase from the 39 percent who said so in April. An additional 22 percent named energy problems _ an enormous rise from the 4 percent who expressed this concern last spring.

The focus on Iraq and international affairs has faded, with just 15 percent naming it as a top issue, down from 25 percent in April and 40 percent in January.

Obama packed more than a half-dozen meetings into his Israel visit, including a stop at the Yad Vashem Holocaust memorial, a helicopter tour of the country and a visit to a house hit by Hamas rockets.

He also rode past an Israeli checkpoint into Ramallah on the West Bank, where he assured Palestinian President Mahmoud Abbas of his support for a two-state resolution of the region's long animosities. Later, entering a session with Israeli Prime Minister Ehud Olmert, Obama said his talks with Abbas indicated ``there's a strong sense of progress being made'' toward peace. Olmert nodded and said, ``Indeed.''

Before dawn Thursday in Jerusalem, Obama prayed at the Western Wall, the holiest place in Judaism.

He was scheduled later in the day to leave for Germany, where he is to deliver an outdoor speech before a large crowd. He also has stops planned for France and England before flying back to the United States on Saturday.