U.S. Democratic presidential candidate Barack Obama pledged staunch support for Israel during a visit to Jerusalem on Wednesday and said, if elected, he would work to invigorate the Middle East peace process.

As part of an overseas tour aimed at bolstering his foreign policy credentials, Obama met Israeli Defence Minister Ehud Barak and right-wing opposition leader Benjamin Netanyahu.

Netanyahu, a former prime minister, said Obama promised never to seek to damage Israel's security. Both men agreed on the "primacy" of preventing Iran from becoming a nuclear power.

Obama was due later to see President Shimon Peres, Foreign Minister Tzipi Livni and Prime Minister Ehud Olmert, who could be forced out of office by a corruption probe.

"I will share some of my ideas. The most important idea for me to reaffirm is the historic and special relationship between the United States and Israel - one that cannot be broken," Obama said on arrival on Tuesday night.

Obama, who faces Republican John McCain in the November election, is struggling to overcome wariness among some Israelis and some Jewish voters in the United States about the strength of his commitment to Israel.

Obama also dismayed Palestinian leaders when he said last month that Jerusalem should be Israel's "undivided" capital.

Palestinians want Arab East Jerusalem, captured by Israel in 1967, as the capital of a future state. Obama later said he used "poor phrasing" when he made the remarks.

The Democratic candidate, an Illinois senator, will visit the occupied West Bank to meet Palestinian President Mahmoud Abbas and Prime Minister Salam Fayyad.

Palestinian negotiator Saeb Erekat said he hoped Israel and the Palestinians would forge a statehood agreement by the time U.S. President George W. Bush steps down in January. If not, he hoped his successor would "stay the course" to pursue peace.

"SPECIAL RELATIONSHIP"

Obama arrived in Israel just hours after a Palestinian rammed a bulldozer into vehicles on a busy Jerusalem street near the hotel booked for his stay. The attacker wounded at least 16 people, one seriously, before being shot dead.

He said the bulldozer attack was "just one reminder of why we have to work diligently, urgently and in a unified way to defeat terrorism".

Obama also expressed his wish to reinforce the "historic special relationship between the United States and Israel".

On earlier trips to Iraq and Afghanistan, Obama underscored his goal of bringing U.S. troops home within 16 months and giving more attention to Afghanistan.

Obama, who plans to visit Berlin, Paris and London next, said on Tuesday he would work vigorously for a peace deal between Israelis and Palestinians but said it would not be easy.

Obama will stop on Wednesday in the Israeli town of Sderot, which sits near the border with the Hamas-ruled Gaza Strip and has been hit by rockets fired by Palestinian militants. McCain visited Sderot in March and did not visit the West Bank.

The cross-border rocket attacks, and Israeli military operations in the Gaza Strip, have largely subsided since an Egyptian-brokered ceasefire took hold last month.

Doubts among Israelis about Obama have been fuelled in part by his pledge to increase engagement with Israel's arch-foe Iran, though he has emphasised any discussions would carry a tough message that Tehran must halt sensitive nuclear work.