TRENTON — A new poll shows Cory Booker leading among likely Democratic voters surveyed in New Jersey's primary for U.S. Senate.

The Monmouth University poll released Tuesday shows 49 percent of Democrats likely to vote in the Aug. 13 primary support Booker.

That's a 37-point lead over his closest competitor, Congressman Frank Pallone, who gets 12 percent of the vote. Rep. Rush Holt gets 8 percent. Assembly Speaker Sheila Oliver gets 3 percent.

The poll shows more than a quarter of likely voters are undecided four weeks before the special election primary to fill the seat of Sen. Frank Lautenberg, who died in office in June.

The telephone survey of 403 registered Democrats was conducted July 11-14 with an error margin of 4.9 percentage points.