U.S. presidential candidate Barack Obama travels to Berlin on Thursday to give the only public speech of a week-long foreign tour, an outdoor address on transatlantic ties that is likely to draw tens of thousands.

Highly popular in Germany, where he is often likened to former U.S. President John F. Kennedy, the Democratic senator will also meet for the first time Chancellor Angela Merkel, who opposed his initial plan to speak at the Brandenburg Gate.

Instead, Obama will give his evening address at the "Victory Column" in Berlin's central Tiergarten park, down the road but still within sight of the Gate, a landmark that stood behind the Berlin Wall for decades as a potent symbol of the Cold War.

"Hopefully (the speech) will be viewed as a substantive articulation of the relationship I'd like to see between the United States and Europe," Obama told reporters in Israel shortly before leaving for Germany.

"I'm hoping to communicate across the Atlantic the value of that relationship and how we need to build on it."

Relations between the United States and Germany reached a post-war low under Merkel's predecessor Gerhard Schroeder, who strongly opposed the U.S. invasion of Iraq in 2003.

But the conservative Merkel, who grew up behind the Wall in the communist East, has worked hard to repair ties and emerged as one of President George W. Bush's closest allies in Europe.

She said on the eve of Obama's visit that she expected to discuss NATO cooperation, climate change and trade issues with the Illinois senator during a morning meeting at the Chancellery that German officials have said will last about an hour.

They are also expected to discuss Afghanistan and Iraq, the countries where Obama started his Middle East and European tour.

In Kabul on Sunday, Obama described the situation in Afghanistan as precarious and urgent.

LIMITS

He and his Republican challenger for president John McCain have both said Europe must step up its efforts there, but Merkel told reporters on Wednesday that she would tell Obama there were limits to what Germany could do.

The Obama visit has dominated the newspaper headlines in Germany for weeks, even sparking sharp exchanges between Merkel and her foreign minister over whether a speech at the Brandenburg Gate was appropriate.

Merkel has said the landmark -- where President Ronald Reagan famously urged Soviet leader Mikhail Gorbachev to "tear down this wall" -- is a place for presidents, not candidates to speak. Her advisers tried to convince the Obama campaign to hold the speech at a university or other low-key location.

Asked if he had read the Cold War speeches delivered by Reagan and Kennedy in Berlin to prepare for his own trip, Obama said unlike the two presidents, he was just "a citizen".

"Obviously, Berlin is representative of the extraordinary success of the post-war efforts to bring the continent and to bring the West together," he said.

Around 700 policemen will be in place for the visit and city workers have been setting up barriers around the "Siegessaeule", a 230 foot (70 metre) high column built to celebrate 19th century Prussian military victories over Denmark, France and Austria, since Monday.

Crowd forecasts vary widely, ranging from 10,000 to nearly a million. German public television station ARD will broadcast the full 45-minute speech, which starts at 7 p.m. (6 p.m. British time), live.

A Pew Research Centre poll showed Germans favoured Obama over McCain by a 49 point margin. Influential weekly Der Spiegel dedicated its weekend issue to the visit, putting a picture of Obama on the cover and the title "Germany meets the Superstar".