(AP) Barack Obama is going for the gold.

The Democratic presidential contender has decided to buy $5 million in national advertising on NBC during the broadcast of the Olympic games, an NBC spokeswoman confirmed Wednesday. The ads will appear on network and cable channels.

The ad purchase was first reported Wednesday on the Web site of Advertising Age, a magazine that covers the industry.

The Olympics, to be held in Beijing, will open Aug. 8. Such an extensive purchase of ad time would give Obama wide exposure before the Democratic National Convention, to be held the last week in August.

Obama has the resources: He has set fundraising records and reported raising $52 million in June, more than twice the $21.5 million raised by his rival, Republican John McCain.

At the same time, the expenditure is as significant for its reach as for the bold statement it makes. Obama has been airing ads in 18 states, reaching key battlegrounds as well as states that have traditionally voted Republican in presidential elections, including Alaska and Virginia.

A national network ad is highly unusual in politics, because of its expense and because it reaches audiences that are not necessarily targeted by a campaign.

In early February, Obama, then neck-and-neck with Hillary Rodham Clinton heading into the Super Tuesday primaries, aired ads during the Super Bowl in television markets serving 24 states that were in play on Feb. 5 and beyond.

Having defeated Clinton and now serving as his party’s presidential nominee, Obama spent Wednesday in Israel, his only full day there during his trip to the Middle East and Europe. He had more than a half-dozen meetings, 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, paid a predawn visit to the holiest place in Judaism, bowing his head in prayer at the Western Wall and pushing a small note into a crevice in the ancient wall, a custom that is observed by many.

Obama's major focus was clearly reassuring Israelis -- and by extension millions of Jewish voters in the United States -- of his commitment to the survival of the Jewish state. He leads his Republican rival, Sen. John McCain of Arizona, among Jewish voters, but his support falls short of what Democrat John Kerry drew four years ago.

Obama's trip is financed by his presidential campaign, and he flew to Israel from Jordan on Tuesday night about his chartered Boeing 757 emblazoned with his trademark slogan, "Change We Can Believe In."

If his campaign aides were looking for memorable images during the day, they got them, from Obama donning a skullcap at the Holocaust memorial, to President Shimon Peres saying, "God Bless You" outside his official residence, to a stop at a house under reconstruction in Sderot where he saw firsthand the destruction caused by Hamas rockets.

"People are committed," he said, making a fist and thumping his chest three times.

Shielded by intense U.S. and Israeli security, he then traveled a short distance to the local police station. There, Defense Minister Ehud Barak, Foreign Minister Tzipi Livni and local officials showed him racks filled with debris from Hamas rockets that have landed in Sderot in the past seven years. In 2005 Israel withdrew from the Gaza Strip a mile away.

The same racks formed a made-for-television backdrop for a news conference attended not only by U.S. reporters, but also Israelis whose satellite trucks jammed the parking lot across the street.

Eli Moyal, the local mayor, gave Obama a souvenir T-shirt -- merely the latest he has received since he began running for president -- and the senator also came away with a gift of a piece of rocket as artwork, attached to a wooden plaque.

Gaza Hamas official Fawzi Barhoum had a less-favorable response to Obama's visit to Sderot:

"Hamas considers the remarks of the Democratic candidate today to be part of the American policy of bias towards Israel and giving legitimacy to Israeli crimes against our people. His remarks today give cover for the occupation's nonstop crimes against our people."

The subject of Tehran's presumed drive to gain a nuclear weapon -- and the threat that would pose to Israel -- was a recurrent theme throughout the day.

The American presidential candidate said, "Iranians need to understand that whether it's the Bush administration or an Obama administration, that this is a paramount concern to the United States."

He said he favors both "big sticks and carrots" to persuade Iranians to switch course.

"What I have also said, though, is that I will take no options off the table in dealing with this potential Iranian threat. And understand part of my reasoning here.

"A nuclear Iran would be a game-changing situation, not just in the Middle East but around the world. Whatever remains of our nuclear nonproliferation framework, I think, would begin to disintegrate. You would have countries in the Middle East who would see the potential need to also obtain nuclear weapons."

At his news conference, Obama brushed aside a question of whether he had backed off his statement this spring that Jerusalem should be the undivided capital of Israel. Palestinians also lay claim to the city as the capital for any state they establish as the result of peace talks, and the two sides have agreed that the final decision is to be negotiated.

Criticized by Abbas after he made that comment, Obama subsequently amended it. "Well, obviously, it's going to be up to the parties to negotiate a range of these issues. And Jerusalem will be part of those negotiations," he said. He added that "as a practical matter, it would be very difficult to execute" a division of the city.

Abbas issued a statement saying he and Obama had not discussed the issue in their hour together.

Asked by an Israeli reporter about the matter, Obama said, "I continued to say that Jerusalem will be the capital of Israel. And I have said that before and I will say it again. And I also have said that it is important that we don't simply slice the city in half. But I've also said that that's a final status issue."

Obama departs on Thursday for Germany, where he is scheduled 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.