The opening salvo in what promises to be a prolonged battle for the White House begins on Thursday with nationwide commercials to help stop the president’s slump in opinion polls.

After months of fierce attacks by Democrat presidential hopefuls, the once high-flying Bush now trails his yet-to-be-nominated challenger 43% to 48%, according to a CBS News survey at the weekend.

The president himself arrives in Los Angeles on Wednesday to address a conference on faith-based initiatives and to raise funds. Bush has already collected an impressive $150 million for his re-election war chest.

The launch of the television ad campaign follows his speech in Washington on Monday, where the Republican incumbent attacked his Democrat rivals, underscoring the impression that Bush’s re-election campaign begins in earnest this week.

Democrat attacks

The early start is all the more unusual because the Democrats are still wading through state-by-state primary elections to pick a presidential challenger.

"This is exceptionally early, the primary season isn't even over yet," says Professor Lynn Vavreck, an expert in politics and media at the University of California in Los Angeles.

She told Aljazeera.net such active campaigning would normally begin around July or August once the parties' national conventions had confirmed their candidates.

But analysts say sustained assaults on Bush by Democrat presidential hopefuls, who had been expected to spend more time attacking each other, have alarmed the president's campaign advisers.

The two Democrat hopefuls, Massachusetts Senator John Kerry and North Carolina Senator John Edwards renewed their attacks against Bush on Tuesday. But they studiously avoided sniping at each other - despite contesting the day's 10 state primaries as rivals.

Media coverage

John Kerry has renewed his
attack against Bush

Moreover, says Vavreck, the media attention on the Democrat primaries has gifted them substantial coverage that Bush now covets.

"The Republicans have been out of the political landscape for some time," she says. "All people are hearing is 'Get Bush out of the White House' - there's no counter message."

There is scant clear evidence that television campaigns significantly affect voting behaviour, says Vavreck. The aim will be to rally party members' morale, remind voters in general that an election is coming, and try to wrest some media attention away from the Democrats.

At this early stage, the ads are not expected to attack Bush's rivals - the absence of a confirmed Democrat candidate presents a difficult target in any case. Instead, the Bush campaign will focus on his record on national security and tax cuts.

With Bush's fight back now underway, Vavreck says the Democrats recent opinion poll lead "could very well change".

Americans go to the polls in November to decide whether Bush deserves a second term in the White House.