The Republican Party has made big gains among white voters since President Obama was elected in 2008, but not among any other racial or ethnic group, according to a new Pew Research poll.

More than half of all white voters (52 percent) now identify themselves as Republicans, compared with 39 percent who are Democrats. That 13-percentage-point lead is significantly higher than three years ago, when 46 percent of white voters were Republicans, compared to 44 percent of Democrats.

At the same time, the Democratic Party’s dominance among black and Hispanic voters continues. Eighty-six percent of black voters and 64 percent of Hispanics are aligned with Democrats, compared to 8 percent of blacks and 22 percent of Hispanics for Republicans. In 2008, 88 percent of blacks and 66 percent of Hispanics voted Democratic, and 6 percent of blacks and 28 percent of Hispanics for Republicans.

The GOP gains among white voters was most pronounced among the young and the poor, the poll found. Republicans now hold an 11-point lead over Democrats among whites under age 30 (52 percent to 41 percent). Three years ago, Democrats held a seven-point lead at 49 percent to 42 percent. Among low-income voters – families with incomes less than $30,000 -- Republicans have a four-point lead, erasing the 15-point advantage Democrats had in 2008.

But the poll added that the massive GOP gains that helped sweep the party back into power last year haven't continued and that the Republican Party hasn’t expanded from its 28 percent of registered voters since 2008. The number of political independents, however, reached a record high at 34 percent in 2011, and more of them say they “lean” toward the GOP – 16 percent now compared with 11 percent in 2008, the poll found.

When leaners are included with partisans, Democrats have a four-point lead among all registered voters, with 47 percent. That’s down from the 12-point lead Democrats held over Republicans in 2008 with 51 percent of registered voters.