Poll: Vilsack, Harkin in lead By Kathie Obradovich . DES MOINES — Incumbents hold the edge going into the homestretch of the campaign, a statewide poll of Iowa voters shows, including a comfortable, 22-point lead for U.S. Sen. Tom Harkin and a 13-point advantage for Gov. Tom Vilsack. . The telephone poll of likely voters shows Republican Rep. Jim Nussle holding a lead over Democrat Ann Hutchinson in the 1st Congressional District race. . Incumbent Congressmen Jim Leach, Tom Latham and Leonard Boswell hold statistically significant leads over their opponents, but high number of undecided voters still could make a...