Democratic presidential contender Barack Obama vowed Tuesday to work for a breakthrough in Israeli-Palestinian peace negotiations "starting from the minute I'm sworn into office."

In a news conference before departing for Israel, he said any U.S. involvement in peace talks must recognize not only Israel's security concerns but also the economic hardships facing Palestinians.

He said he would continue to regard Israel as a valued ally. "That policy is not going to change," he said.

"What I think can change is the ability of the United States government and a United States president to be actively engaged with the peace process and to be concerned and recognize the legitimate difficulties that the Palestinian people are experiencing right now."

Arriving in Jerusalem later Tuesday, Obama said he hoped his administration would strengthen the historic special relationship between the United States and Israel and, citing a Palestinian attack in downtown Jerusalem earlier in the day, pledged "to work diligently, urgently and in a unified way to defeat terrorism."

Obama, in the midst of a weeklong, high-visibility foreign trek, also acknowledged the long history of Middle East tensions that would confront him if he were to become president.

"It's unrealistic to expect that a U.S. president alone can suddenly snap his fingers and bring about peace in this region," he said.

Obama was in Afghanistan and Iraq before arriving in Jordan on Tuesday for talks with King Abdullah II. After Israel, he is scheduled to travel to Europe.

Jordan's king told Obama that an evenhanded U.S. policy would bolster America's credibility in the Middle East and that achieving Palestinian statehood is essential for ending the Arab-Israeli conflict, according to a royal palace statement summarizing Abdullah's remarks during a closed-door meeting with the Illinois senator at Abdullah's private residence in Amman.

Obama condemned an attack in Jerusalem on Tuesday, where a Palestinian man rammed a construction vehicle into cars and a bus near the downtown hotel where Obama was scheduled to stay. An Israeli civilian shot and killed the driver. Several people were injured in the attack, which resembled a deadly vehicle assault in the city earlier this month.

"Today's bulldozer attack is a reminder of what Israelis have courageously lived with on a daily basis for far too long," Obama said.

Campaign aides said Obama intends to visit a southern Israeli town that is a frequent target of rockets fired by Palestinian militants in Gaza.

The stop in Sderot is part of a crowded day of events on Wednesday in which the Illinois senator also has arranged to meet with Palestinian President Mahmoud Abbas in Ramallah on the West Bank and with Israeli leaders.

Susan Rice, a foreign policy adviser, said Obama wanted to go to Sderot because it is a "place in which Israel's security is every day at risk and threatened. And Sen. Obama will have the opportunity to see that first hand and get a very personal feel for the everyday" difficulties. His schedule indicates he intends to spend slightly more than an hour there.

Obama's trip to Iraq and Afghanistan was an official congressional trip, paid for with federal funds. The balance of his travels are financed by his presidential campaign.

The Illinois Democrat is working to shore up support among U.S. Jewish voters, many of whom supported Hillary Rodham Clinton in the battle for the party's presidential nomination, and some of whom have questioned his commitment to Israel.

Asked about stronger support among Israeli Jews for Republican candidate John McCain, Obama told CBS News that's because his rival is better known. Continued...