Rupert Cornwell: A foreign trip from hell – but Mitt's still well set for his assault on the White House

World Focus: The man who would be president and a week of faux pas

Mitt Romney talks to the media at Downing Street last week (Reuters)

Read the headlines and it was the candidate's foreign trip from hell: a succession of mishaps capped by an expletive-laden tirade from an exasperated aide to an equally exasperated group of travelling reporters. In fact, Mitt Romney's foray to Britain, Israel and Poland is likely to have only the tiniest impact on his chances of winning the White House in November.

Last night President Barack Obama's Republican challenger was heading back to the US from Warsaw, scene of a final brouhaha, as his travelling press secretary lashed out at reporters who yelled questions at Mr Romney after he laid a wreath at Poland's Tomb of the Unknown Soldier.

"Do you have a statement for the Palestinians?" shouted one as the candidate walked back to his car. "Do you feel your gaffes have overshadowed your trip?" yelled another. Mr Romney ignored them, but not so Rick Gorka. "Shove it," he said, before inviting another questioner to "Kiss my ass". The spokesman quickly called the reporters involved to apologise. But the damage was done.

Above all the episode reflected an eternal tension of US presidential campaigns – between reporters grumbling about poor access, and a candidate convinced that the media focuses exclusively on the sensational.

In reality, the political consequences of the dust-up will probably be small. Journalists are not exactly America's most admired community, and the coverage will only reinforce Republicans in the belief that the "mainstream media" is biased against them.

These last five days abroad may not have burnished his credentials as America's diplomat-in-chief as they were designed to do. But that would have been hard to achieve, given Mr Obama's commanding lead – so rare for a Democrat – over Mr Romney when voters are asked which candidate they most trust to handle foreign policy.More fundamentally, foreign policy issues do not decide US elections. This year that is truer than ever, with high unemployment and a sluggish economy the overriding concern for voters.

Yes, the Republican candidate infuriated Palestinians by saying that Jerusalem should be Israel's capital, and suggesting that "cultural" differences explained why Israel had a per capita GDP double that of the rump Palestinian state (in fact the true differential is roughly 10-to-one). However no US presidential candidate ever lost votes by criticising or belittling the Palestinians.

In Britain, he may have gratuitously insulted a key US ally by suggesting London was not ready to host the Olympics – but, like Palestinians, British citizens do not vote in American elections. At every stop, Mr Romney's target audience was not the local one, nor even America's foreign affairs community, but the one back home.

In Israel, his lavish professions of fealty to the Jewish state were designed to reassure Christian conservatives in the US, a vital Republican constituency committed to the Israeli cause and often sceptical of Mr Romney's conservative credentials. Party strategists also hope to win over a sliver at least of the American-Jewish vote, in the past overwhelmingly Democrat, but less supportive now of Mr Obama.

Nor was it an accident that Mr Romney went to Poland, ancestral home of the Polish-American voters heavily represented in "rust belt" states such as Wisconsin, Michigan Pennsylvania and above all Ohio, where the 2012 election may be decided.

If anything, the controversies generated by the Republican challenger's trip have confirmed what was already obvious. However hard he tries, Mr Romney seems to carry a tin ear everywhere he goes. His eye has been on the White House for a decade or more. His managerial competence is one of his main assets. He runs a campaign extraordinarily disciplined even by American standards. But, time and again, he manages to lurch off script.

Off message: Romney's week of gaffes

"The stories about the private security firm not having enough people, the supposed strike of the immigration and customs officials – that obviously is not something which is encouraging"

25 July: Unlike the UK, and much of the world, Romney shows he can contain his excitement as he arrives in London for the Olympics

"Like you, Mr Leader, I look forward to our conversations this morning"

25 July: For once Ed Miliband was not the most awkward man in the room, as Romney appeared to forget the Labour leader's name during their joint press call

Jerusalem is "the capital of Israel"

29 July: After riling Palestinian officials by telling campaign donors at a fund-raiser in Jerusalem that "culture" and "providence" were reasons why Israelis were more economically successful than Palestinians, he then declares the disputed city to be Israel's

"Kiss my ass"

31 July: This time it was Romney's spokesman, Rick Gorka, who lost his cool with reporters on a visit to the Tomb of the Unknown Soldier in Warsaw, after they pressed him on why Romney declined to answer their questions