Obama leads among Democrats

PRINCETON, N.J., March 31 (UPI) -- Presidential hopeful Barack Obama has extended his lead over rival Hillary Clinton among Democrats, a poll indicates.

A Gallup Poll Daily Tracking report suggests the Illinois senator leads his New York colleague 52 percent to 42 percent, marking his widest lead this year, Gallup said.

The results are based on polls conducted from March 27-29, in which Gallup interviewed 1,128 adults. The margin of error is plus or minus 3 percentage points.

Gallup also found that Arizona Sen. John McCain, the presumptive Republican nominee, has a four-point lead over Clinton. McCain leads Obama by three points, 47 percent to 44 percent, Gallup said.

The results are based on 4,407 interviews from March 25-29. The maximum margin of sampling error is plus or minus 2 percentage points.