MANCHESTER, New Hampshire (CNN) -- Democratic presidential front-runner Sen. Hillary Clinton's once double-digit lead in the key primary state of New Hampshire has eroded substantially since February, while rival John Edwards has made a run toward the front of the pack, according to a new poll released Tuesday. (Read full poll results [PDF])

The CNN/WMUR presidential primary poll, conducted by the University of New Hampshire, found that Clinton was the choice of 27 percent of likely Democratic voters in the Granite State, down from 35 percent in the same poll in February. Meanwhile, Edwards, who was the choice of just 16 percent in February, saw his support jump to 21 percent, vaulting him past Sen. Barack Obama into second place.

The poll's sampling error of plus or minus 5.5 percentage points means that Clinton and Edwards are in a statistical dead-heat at the front of the pack, along with Obama, who came in at 20 percent, the poll found. The Illinois senator was at 21 percent in February.