By Debbie Hummel
SALT LAKE CITY (Reuters) - Veteran Senator Orrin Hatch faced off on Tuesday against a Tea Party movement-backed challenger who was able to woo enough votes at Utah's Republican nominating convention to force a primary run-off.
Hatch, a 78-year-old stalwart of the Republican Party who was first elected to the Senate in 1976, will compete against Dan Liljenquist, a former state senator who has billed himself as a face for change and more conservative leadership.
Heavily Republican Utah last elected a Democrat to the U.S. Senate more than four decades ago, so the victor in the state's Republican Party contest is usually considered the presumptive winner of the general election in November.
"We feel very confident that the campaign has been run and our message has gotten out to the voters in the state and they are supportive of the senator," Hatch spokesman Dave Hansen said, citing polls that showed the incumbent leading handily going into Tuesday's election.
Hatch came out with the most votes over nine challengers at the April convention but narrowly fell short of the 60 percent needed to win the party nomination outright and avoid the primary.
Hatch, who has vowed this will be his last race for the Senate, said his seniority and likely chairmanship of the Senate Finance Committee, make returning him to Washington a priority for Utah voters.
Liljenquist, 37, said in a recent radio debate that he was running against Hatch because of the senator's seniority, not in spite of it.
"In the 18 years on that Senate Finance Committee, you have voted yourself to expand entitlements by trillions of dollars," Liljenquist said.
Liljenquist has said more conservative leadership is needed, adding his youth and commitment to change in Washington make him the logical choice over the six-term senator.
He and state Representative Chris Herrod, who was among the field of early challengers, gained a Tea Party following for campaigning for cutting taxes and reducing the size of government.
Another long-time Utah Republican senator, Bob Bennett, was ousted in a Tea Party drive at the state's convention in 2010, leading to the election of Senator Mike Lee. Tuesday's vote will be a test of sway for Tea Party activists, who played a decisive role nationally in the 2010 mid-term elections.
One poll, conducted in mid-June by Key Research with faculty from the Center for the Studies of Elections and Democracy at Brigham Young University, showed Hatch favored by about 60 percent.
The winner of the primary will go on to face conservative Democrat Scott Howell, also a former state senator.
(Editing by Cynthia Johnston and Vicki Allen)