U.S. President Barack Obama started out his presidency with a 68 per cent job approval rating, but this has dropped to 50 per cent going into 2010, according to Gallup. (Charles Dharapak/Associated Press)

U.S. President Barack Obama began his second year in office with the second lowest job approval rating and highest disapproval rating of any president at that point in their term over the past 50 years, according to Gallup.

But the ratings do not necessarily predict political failure, since other presidents with low polling numbers in their second year have gone on to win re-election.

According to Gallup, Obama started out his presidency with a 68 per cent job approval rating. But that has dropped to 50 per cent going into 2010.

Only former president Ronald Reagan had a lower job approval rating among presidents beginning their second year in office. Reagan started his second year with a 49 per cent approval rating.

But Obama's disapproval rating is higher than Reagan's (44 per cent to 40 per cent).

Gallup went back as far as Dwight Eisenhower in 1954 in its comparisons.

Despite Reagan's low approval ratings, he went on to win a landslide victory in his re-election bid. Both Reagan and Obama faced economic challenges coming into their presidencies.

Former president Bill Clinton, whose job approval rating was 54 per cent going into his second year, also went on to win re-election.

And George Bush Sr., who had one of the highest job approval ratings (80 per cent), eventually lost to Clinton.

"The meaning of the 50 per cent threshold is somewhat relative," Gallup said on its website. "A 50 per cent job approval rating would have been cause for major celebration by George W. Bush for much of his second term.

"But given the speed at which Obama descended to this level in his first year, today it is more of a warning light that this initially muscular administration remains on the threshold of losing majority support."

The survey of 3,032 people was conducted between Jan. 2 and Jan. 4, 2010, and has a margin of error of plus or minus two percentage points, with 95 per cent confidence.

Interviews were conducted with respondents on land-line telephones and cellular phones.