Washington, Dec 14 (IANS): In a dozen key swing states across the United States, Democratic President Barack Obama is trailing his two leading Republican rivals hoping to challenge him in 2012 presidential election, according to a new opinion poll.

While former Massachusetts Governor Mitt Romney led Obama by 5 percentage points, former House speaker Newt Gingrich led by 3 percentage points, according to Gallup/USA Today poll released Tuesday.

The survey, which included Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia and Wisconsin, found that Obama is running behind Romney, 43-48 percent, while he is losing to Gingrich, 45-48 percent.

The results from the dozen swing states are worse for Obama than his performance nationwide, where he leads Gingrich by 6 percentage points and Romney by a single point, the poll says.

Meanwhile, the survey also showed the number of Democrats declined in the swing states while the number of Republicans rose since 2008, painting a drastically different electoral landscape for the president's 2012 re-election efforts.

In the dozen key states, the number of self-identified Democrats in these key states fell from 35 percent to 30 percent since 2008.

During the same period, the number of Republicans rose 5 percentage points, while the number of independents increased by a whopping 7 points - from 35 percent in 2008 to 42 percent. In the 12 swing states, 44 percent of those surveyed are conservatives and 21 percent are liberal.

"In 2008, when Obama carried the swing states by 8 percentage points, Democrats there swamped Republicans in party identification by 11 points. Now, that partisan edge has tightened to a statistically insignificant 2 points," the analysis of the poll says.

Obama's other challenge as he tries to secure another four years at the White House is the 61 to 47 percent enthusiasm gap between Republicans and Democrats over the presidential election.