Washington, D.C. ? Barack Obama has taken clear leads over Hillary Rodham Clinton among white men, middle-income earners and liberals, allowing him to catch his faltering rival in their race for the Democratic presidential nomination, a national poll showed Monday.

The Associated Press-Ipsos survey highlights how the bottom is falling out among some supporters of Clinton, the New York senator, since the last survey was taken two weeks ago. Since that poll, Obama has gained momentum by winning 11 consecutive primaries and caucuses while taking a small lead among delegates to the party’s convention this summer.

The Illinois senator leads Clinton by 23 percentage points among white men and by 17 points among liberals – groups that were evenly divided between the two in early February.