Barack Obama embarks this weekend on a tour of Europe, the Middle East and Afghanistan — a feverishly anticipated audition on the world stage that includes the unprecedented spectacle of an American presidential candidate addressing a huge crowd in a foreign city.

Yet, for all the adoring throngs that are likely to greet the Democratic contender and the eight foreign leaders he will meet, the trip is aimed at voters back home, where Mr Obama’s youth and inexperience have raised significant doubts that he has the gravitas, grit and sure-footedness to be their next commander-in-chief.

The 12,000-mile whirlwind tour, extraordinary for its timing midway through a general election campaign and the international media frenzy it is attracting, will take Mr Obama to Iraq, Afghanistan, Jordan, Israel, the West Bank, Germany, France and Britain as he seeks to bolster his national security credentials — one of his greatest electoral liabilities.

Should any of his hosts be under the illusion that the trip is not primarily a White House campaign event, Mr Obama, 46, is taking no foreign journalists. Instead, he has filled his campaign plane with US reporters, including three television news anchors, who are in discussions to hold prime-time interviews with him on consecutive nights.

It is a sobering contrast for John McCain, his Republican opponent, whose European and Middle East trip in May garnered scant coverage.

In London a week tomorrow, the last leg of the trip, where Mr Obama is likely to spend less than a day, he will meet Gordon Brown at 10 Downing Street and then David Cameron, and will briefly shake hands with a few campaign contributors.

His British visit comes amid anxieties in Whitehall about how strong a commitment to the “special relationship” a President Obama would make. There have been signs that he views France and Germany as more at the heart of Europe, rather than Britain, a country he has only fleetingly visited twice. There is also a sense that Mr Brown has been eclipsed in American eyes by Angela Merkel, the German Chancellor, and President Sarkozy of France.

Indeed, the significant event of the trip will be an address next Thursday in Berlin before what is expected to be a massive crowd in a country where Mr Obama enjoys approval ratings that Mrs Merkel could only dream of, and where his aides hope that comparisons to a young John F. Kennedy electrifying the city in 1963 will be clear.

Choreographing the Berlin speech has been fraught with tensions and diplomatic blunders. The Obama campaign initially sought to hold it at the Brandenburg Gate, where Ronald Reagan — as President — declared in 1987: “Mr Gorbachev, tear down this wall!” Mrs Merkel expressed her distaste at the idea of a White House candidate using one of Berlin’s most famous landmarks as the backdrop for a speech. Her spokesman said that she felt “displeasure” at the idea, adding that no German politician running for high office would dream of using the National Mall in Washington for a public event.

Mr Obama’s aides, who now concede that the Brandenburg Gate idea was a poor one — and perhaps smacked of arrogance — are understood to be searching for a new site.

Mr Obama has been taunted by Mr McCain for having visited Iraq only once — in 2006 — and never setting foot in Afghanistan. In a speech this week he repeated his vow to withdraw US combat troops within 16 months — a timetable opposed by No 10 — and to refocus on Afghanistan, a war that he said “we must win”.

His trip to Iraq and Afghanistan has been shrouded in secrecy for security reasons but has significant implications for London, Paris and Berlin. One of his first international acts as president would be to demand more European troops and money for Afghanistan, a conflict where he might rapidly discover, like previous US presidents, that in matters of war Britain is America’s most reliable ally.

On the Iraq leg of his trip, Mr Obama is taking with him Jack Reed, a Democratic colleague in the Senate and former army officer, and Chuck Hagel, a Republican senator who has been highly critical of the Iraq war and has been touted as a possible bipartisan vice-presidential choice.

In Baghdad, the group will meet the Prime Minister, Nouri al-Maliki, and President Talabani, and will receive a briefing from General David Petraeus, the US ground commander.

Yesterday Mr McCain repeated criticisms that he made of Mr Obama on Tuesday, mocking him for laying out his Iraq strategy before he had visited the country. The normal way to proceed, he said, was to get the facts on the ground before announcing the policy.

In Jordan, King Abdullah is expected to get a promise from Mr Obama that, if elected, he will place a high priority on invigorating Arab-Israeli peace talks.

Mr Obama will then step gingerly into the minefield of the Arab-Israeli conflict with a visit to Jerusalem and the West Bank town of Ramallah, where every statement and gesture will be scrutinised.

Israelis have been uneasy about Mr Obama amid perceptions that he is sympathetic to the Palestinian cause and because of his willingness to talk with the Iranian leadership. In a recent speech to a US Jewish lobbying group, Mr Obama, seeking to prove his pro-Israeli credentials, declared that Jerusalem should be the “undivided” capital of Israel, which alarmed Palestinians and appeared to pre-judge final-status talks.

He has since backtracked from that remark and is likely to seek to clarify it when he meets Mahmoud Abbas, the Palestinian President, in Ramallah on Wednesday. In Jerusalem he will meet the Israeli President, Shimon Peres, the Prime Minister, Ehud Olmert, the Defence Minister, Ehud Barak, and the opposition Likud leader Binyamin Netanyahu. He is expected to visit the Wailing Wall.

Mr Obama’s aides know that their candidate will be greeted in Europe by an adoring public, producing images that they hope will persuade voters that he is the right man to restore America’s international reputation and repair frayed relations.

Yet he leaves behind a tough campaign at home — he enjoys only a small lead over Mr McCain in polls — and a country where being loved by Europeans is not always a key to success. John Kerry, Mr Bush’s 2004 opponent, was even ridiculed by Republicans for “looking French”. Any mistake or faux pas could increase perceptions that he is not yet ready for the Oval Office.

Mr Obama, who is not taking his wife Michelle on the trip, did receive a boost on the campaign front yesterday. His staff announced that he raised $52 million (£26 million) last month, reversing a downward trend in his recent efforts to boost funds. Mr McCain raised $22 million last month, his best fundraising performance of the year.

Jill Hazelbaker, Mr McCain’s spokeswoman, said of Mr Obama’s trip: “Let’s drop the pretence that this is a fact-finding trip and call it what it is: the first-of-its-kind campaign rally overseas. It’s a giant photo opportunity.”

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