WASHINGTON (Reuters) - More than two-thirds of Americans disapprove of the way President Barack Obama is handling high gasoline prices but most do not blame him for them, according to a Reuters/Ipsos online poll released on Tuesday.

Sixty-eight percent disapprove and 24 percent approve, according to the poll, taken on Monday and Tuesday. Rising fuel costs are shaping up as one of the biggest issues in the 2012 presidential campaign, as U.S. gasoline prices have jumped about $0.30 per gallon to just over $3.90 within the past month.

Majorities of voters from both parties and independents all disapprove of the Democratic president's handling of gas prices, according to the online poll, spelling potential trouble for Obama in the November 6 election.

Eighty-nine percent of Republicans disapprove, as did 52 percent of Democrats and 73 percent of independents.

But respondents were more likely to blame oil companies that want to make too much profit - rather than politicians - for high gas prices.

(Reporting By Patricia Zengerle; Editing by Bill Trott)