Hansen said the 36-year incumbent doesn't need to prove anything about his health or energy level.
"Senator Hatch has been a public person for many years. People see him every day either in Utah or Washington, D.C., or elsewhere. He is in great health, great shape. This past year especially he has been all over this state. Voters have had a chance to talk with him, be with him," and judge for themselves what kind of shape he is in.
Howell made his challenge after The Salt Lake Tribune reported in a blog that former Sen. Bob Bennett, R-Utah, 79, said Howell, too, could die in office if elected a response to a fundraising email Howell sent earlier this week telling supporters Hatch was too old to handle America's modern needs and that he could "die before his [next] term is through."
Bennett said he had seen younger senators die in office, and older senators who managed to serve their full terms. Bennett declined to guess about Hatch's longevity.
But Howell used the comments to make his challenge for release of medical records.
"We should not make guesses," Howell said. "The records will speak for themselves."
Earlier this week, after the initial flap over the "Hatch could die" email, Howell also attacked a comment by Hansen in a TV interview on Hatch's age where he noted that The Church of Jesus Christ of Latter-day Saints is led by "some people who are not exactly youth who are doing a magnificent job."
That led Howell to say in a news release that the LDS Church releases most general authorities at age 70, and only apostles and members of its governing First Presidency serve at older ages.
"If Orrin or his campaign believes he is or should be part of that group," Howell said, "they are truly misguided."
He added that bishops in the LDS Church typically serve five to six years, and stake presidents usually serve no more than 10 years and said Hatch has served many times that. "The Founding Fathers never intended for public service to be a lifelong profession," he said.