Call it the Potomac shuffle, the traditional election-year dance in which a candidate who has earlier moved left or right to win over the party faithful in a primary campaign promptly slides back to the centre to appeal to the rest of the country. Barack Obama, quite a mover on the

dance floor, has spent the month since he beat Hillary Clinton to the Democratic nomination giving a demonstration of this time-honoured piece of Washington choreography .

On July 1, he announced, in a speech on religion aimed at wooing evangelicals — who Democrats believe are no longer a guaranteed bloc for the Republicans — that he would continue George Bush’s support for “faith-based initiatives”, channelling public money to religious groups to perform social services, whether drug rehab or care for the homeless. A day earlier Obama had delivered an equally long address on the virtues of patriotism. On his lapel was the flag pin he has worn since mid-May, the same pin he once disdained as an unnecessary, shallow display of love of country. More substantively, Obama has tacked towards the centre on a string of issues where a matter of months ago he was to be found much further left.

He once opposed legislation needed for Bush’s much-reviled programme of domestic surveillance; now he supports a new law that would grant immunity to phone companies that help the government eavesdrop on US citizens. He was an advocate of gun control, but only hemmed and hawed when the supreme court delivered its landmark endorsement of the individual’s right to bear arms last week. He now says he will consider joining his Republican opponent John McCain in calling for a cut in the corporate tax rate.Suffice to say, these were not positions Obama took when he was trying to win Democratic votes in New Hampshire or Iowa.

Bill Clinton could finesse shifts by wrapping them in the language of policy detail; Obama is the very opposite of a policy wonk operating at 30,000 feet, somewhere in the rhetorical stratosphere. While the Clinton of 1992 talked obsessively about the economy, ensuring hard-pressed voters knew he felt their pain, Obama has not yet persuaded Americans that he is the answer to current woes. One Democratic strategist thinks Obama should be talking about rising gas and food prices, not making grand speeches about faith or patriotism.

Indeed, Obama’s sheer eloquence, combined with the string of recent policy flip-flops, points to another worry many Democrats are beginning to voice about their nominee: that there might be a hollowness to him, an absence where there should be a clear core of belief. In this light, Obama’s U-turns look different. They suggest that he is determined not to be just another principled loser - and the Democrats have had plenty of those. The clearest illustration came in Obama’s most blatant reverse.

He had promised to stay within the system of taxpayer-funded campaign finance, which would have obliged him to stick to an $85m spending limit. Once it became clear he could raise, and spend,he broke his pledge. Sure, it was unprincipled. But it suggested a man bent on winning and ruthless enough to make sure he does. That’s the standard operating procedure for Republicans. For Democrats it takes some getting used to. — The Guardian