Barack Obama's support falls among white voters

His support among white voters fell to below 50 per cent for the first time in his presidency following his accusation the police "acted stupidly" in arresting a black Harvard professor,

A Pew research poll found that 53 per cent of white voters approved of Mr Obama's job performance before his prime-time intervention in the furore over whether Sergeant Joseph Crowley, a white officer, was right to arrest Henry Louis Gates Jr, a black studies professor.

This dropped to 46 per cent in just two days as many white supporters reacted with dismay to Mr Obama's statement, which he tried to rectify by arranging a "beer summit" at the White House in which he and Vice President Joe Biden sipped their chosen brews in the Rose Garden under the gaze of the media.

Mr Obama's overall popularity remains just over 50 per cent but his failure to secure a health care bill before the August congressional recess, partly attributable to the distraction caused by the race debate, could be an ominous portent.

Andrew Kohut, head of the Pew Research Centre, said that Mr Obama needed a legislative victory or a change in the economic downturn for his political fortunes to improve. "They need to give people some sense of success. If the economy begins to improve, that will help enormously."

The success of Mr Obama's presidential campaign was based on his ability to win an overwhelming proportion of black voters while at the same time securing broad support among white voters, many of whom were attracted by the Illinois senator's appeal to a post-racial future.

White voters also acted on what they saw as their economic self-interest with the so-called Reagan Democrats - blue-collar industrial workers in economically hit Rust Belt - putting aside reservations about voting for a black man.

During the campaign, Mr Obama seldom spoke directly about race, recognising that if he was defined as the "black candidate" he would be defeated.

His act of plunging himself into a racial controversy such as the Gates incident therefore mystified allies and foes alike and have left him more vulnerable to dissent from Congress.

Lawrence Jacobs, director of the University of Minnesota's Hubert H. Humphrey Institute of Public Affairs, described the episode to the Associated Press as "the first major personal debacle for the president".