John McCain was today basking in strongly improved opinion poll ratings after his running mate Sarah Palin wowed the Republican National Convention last week.

A USA Today/Gallup poll put Mr McCain four points ahead of Barack Obama, his Democratic rival, by 50 per cent to 46 per cent, in polling that took place over the weekend – after Ms Palin's highly successful speech.

Analysts said that Mr McCain's bounce in the polls was to be expected, as candidates almost always see a poll surge after their party convention.

The size of the swing was however being attributed to the Palin effect, as the impact of the Governor of Alaska's sudden arrival on the political scene began to filter through to potential voters.

A USA Today poll taken before the Republican convention opened had Mr McCain trailing Mr Obama by 7 per cent.

Mr McCain yesterday paid tribute to his new running mate, claiming “the electricity has been incredible” at rallies ever since he invited Ms Palin to join his ticket. He told CBS: “She has excited people all over the country. I would love to say it was all because of the charisma of John McCain, but it is not. I’m sure Governor Palin has failings, we all do. But she is what Americans have been looking for.”

Overall, Mr McCain has moved ahead of Mr Obama for the first time since January, according to a poll of polls on the RealClearPolitics website.

Ms Palin faces another major test this week when she gives her first nationally televised interview. Her personal life has come under intense scrutiny in the last ten days, but a torrent of revelations, including news that her 17-year-old daughter is pregnant, but intends to marry the father and keep her baby have appeared to add to, rather than detract from, her popularity.

Mr Obama has for the first time in many months found himself struggling to regain voters' attention. He has attempted to respond to the new Republican challenge by vowing to focus his efforts on the economic crisis facing ordinary Americans.

The Democratic nominee, whose presidential campaign has often been dominated by his compelling life story, has now discovered a distaste for personality politics. “You know, this whole résumé contest is not what the American people are looking for,” he said. “I have to make it clear what is at stake in this election.”

Campaigning in Indiana at the weekend, Mr Obama scorned his opponent’s efforts to seize the mantle of change. He pointed out that Mr McCain’s campaign was stuffed full of former corporate lobbyists and that Mrs Palin herself had employed them to introduce federal funding – called “earmarks” – into legislation. To suddenly portray herself as the “champion anti-earmark person” was risible, he said. “That’s not change. Come on! I mean, words mean something, you can’t just make stuff up.”

Yesterday, in an interview on ABC, he concentrated on America’s ailing economy, saying that unemployment figures, as well as the crisis surrounding mortgage giants Freddie Mac and Fannie Mae, had demonstrated the fragility of the US economy. The Republican convention in St Paul last week had, he added, nothing to say about key issues such as health care, making college more affordable or keeping people in their homes.

He mocked Mr McCain’s effort to distance himself from an unpopular White House Administration, claiming that his choice of Mrs Palin had demonstrated the Republicans were still driven by right-wingers who would “have had a riot” if a centrist running-mate like Senator Joe Lieberman had been chosen instead.

Mr Obama still had to deal with issues about his own views and exotic background, disclosing that he had once considered joining the US military and then acknowledging that, when asked last month at an evangelical forum if life began at conception, he had been too flippant in replying it was “above my pay grade”. He said yesterday: “What I intended to say is . . . I don’t presume to be able to answer these kinds of theological questions.”

He also repeated a previous charge that Republicans were seeking to smear him over his religion, alleging that they had been “very good at throwing rocks and hiding their hand” when discussing “my Muslim faith” – before swiftly correcting himself to say “my Christian faith”.

Mr McCain similarly sought to focus on so-called pocketbook issues when he appeared on CBS. Despite previously stating that the economy was “basically sound”, he said that the news on Fannie Mae and Freddie Mac showed why “Americans are hurting in a way that they have not hurt for a long time”.

His party spent much of the weekend relishing a row over the refusal of Oprah Winfrey, a strong supporter of Mr Obama, to have Mrs Palin on her daytime TV show, and trying to capitalise on the fact that Ms Palin had so far not put herself up for television interview. But the Republicans countered by saying that Ms Palin would speak to ABC this week.

David Axelrod, Mr Obama’s chief strategist, hinted at his irritation over the way Mrs Palin had overshadowed the Democratic campaign in the past week, saying: “This, ultimately, is not a race between us and Sarah Palin. It is a race between Barack Obama and John McCain.”

Times Recommends

• Tehran cannot live up to its rhetoric
• The new unicycle that will ‘change the world’
• We cannot wish away Iran’s bomb