Read the full Reuters/C-SPAN/Zogby daily tracking poll

The race for the Democratic presidential nomination tightened slightly over the last 24 hours, but Senator Hillary Clinton retained her edge over rivals Barack Obama and John Edwards, a new Reuters/C-SPAN/Zogby daily tracking poll in Iowa shows. With a 3.3 percent margin of error, Hillary Clinton leads Barack Obama 31 percent to 27 percent with John Edwards at 24 percent. On the Repulican side, with the same margin of error, Huckabee leads Romney 29 percent to 28 percent, with John McCain the only other candidate in double digits at 11 percent.