While Barack Obama was being feted in Berlin, there were many voters back in the US wondering what he was doing in Europe at a time when their homes are being repossessed and jobs cut.

With Europeans clearly favouring Mr Obama over his Republican rival John McCain, the reality back in America is that their presidential race is close, with many voters still harbouring significant doubts about the Democrat's lack of experience and core values.

Although it is early days in the general election campaign, and with Mr Obama still favoured to win, the polls show that since he captured his party's nomination a month ago, Mr McCain has actually gained ground on his opponent.

Such a dynamic is all the more surprising because Mr McCain has suffered a bad fortnight. His campaign co-chairman resigned after calling Americans worried about the economy "whiners"; his opposition to a timetabled withdrawal in Iraq is in danger of being eclipsed by events on the ground; and a series of gaffes and sheer bad luck have contrasted poorly with Mr Obama's almost flawless foreign tour.

Yet a Wall Street Journal/NBC survey has underscored voter unease with Mr Obama and the fact that his poll lead over Mr McCain remains small, in part because more Americans identify with Mr McCain's "background and values" than with Mr Obama's. Many voters feel that they still don't know Mr Obama.

The poll gave Mr Obama a six-point lead over Mr McCain, but the Republican held significant advantages on the issues of experience, who would make a better commander-in-chief and leadership. They key question for voters was what type of president Mr Obama would make, indicating that if he can quell lingering doubts, he could win handsomely - but if those doubts grow, Mr McCain has a great chance of victory.

While Mr Obama met with Israeli and Palestinian leaders on Wednesday, Mr McCain was holding a campaign rally in north-eastern Pennsylvania, in a reliably Democratic region.

"For the past two days on talk radio here, pretty much every caller wanted to know why Barack Obama was in Europe and the Middle East rather than talking to people back home about the issues here," said Andrew Seder, a reporter for the Times Leader in Wilkes Barre who covered the McCain event.

With record-high petrol prices, rising unemployment, and a gloomy economy, Mr Seder said: "They just don't understand why he's over there right now. They see the trip as a political stunt."

Mr Seder said that the normally reliably Democratic area was up for grabs this year, because of doubts about Mr Obama. "A lot of Democrats were in the McCain audience and are going to vote for him," Mr Seder said. "I haven't figured out if it's a racial thing, his experience, or his lack of ties to the military, but a lot of people just can't get on board for Obama."

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