The latest Quinnipiac University survey of Iowa underscores the up-for-grabs nature of the race, finding a three-way statistical tie for first place, with Sen. Elizabeth Warren (D-Mass.) at 20 percent, followed by South Bend, Ind., Mayor Pete Buttigieg at 19 percent, Sen. Bernie Sanders (I-Vt.) at 17 percent and former Vice President Joe Biden at 15 percent.