The governor said he intends to make his decision "in conjunction with the Legislature. They convene in January 2014. That's when I'm going to make the decision."
The federal Department of Health and Human Services has set no hard deadline for states to make a call about expanding Medicaid, but the state risks losing millions in funding if its determination lingers past the fall.
Utah is among a handful of states that have yet to decide. Herbert said he is still gathering information about the "actual true cost" of an expansion.
"We have decisions being made in this country today on health care, particularly on the Affordable Care Act, on Medicaid expansion, being based on political rationale," Herbert said, "as opposed to what is common sense and what is in the best interest of the people and the taxpayer."
Up to 123,000 of Utah's 400,000 low-income uninsured would get coverage if Medicaid were expanded to cover those earning up to 138 percent of the poverty level about $32,400 for a family of four, or $15,856 a year for one person.
In states that opt for full expansion, the federal government will pay 100 percent of those costs through 2017. After that, states will pay a share, but the law caps those expenses at 10 percent of overall costs.
Utah's Republican lawmakers oppose a full expansion, while advocates for the poor and some medical providers favor it.
Herbert's timetable "isn't a big surprise," but it leaves the state and its poorest residents at some disadvantage, said Mattt Slonaker of the advocacy group Utah Health Policy Project.
Millions of federal tax dollars paid by Utahns will be lost if the state fails to expand, and many of the uninsured will remain unable to access insurance, he said. About half of the Utahns who would be eligible for Medicaid under an expansion or about 60,000 people earn less than 100 percent of the federal poverty level, and they won't be eligible to buy insurance through the new online insurance marketplaces.
"Every six months we delay, we're missing out on a very generous federal match and all of those benefits that other governors and legislatures have moved to maximize," said Slonaker. "We'll be helping folks sign up for health insurance, but a number of those will have to be told 'I'm sorry, you have no options.'"
Herbert has charged a community work group with drafting a range of options. The group's final report is expected on Sept. 26, when Herbert holds his annual state health summit.
Utah also has received an independent cost-benefit analysis, released in May, that said the state could save $131 million during the next 10 years if state officials opt to fully expand Medicaid.
But Herbert said he still has questions and concerns, noting the decision will impact Utah for generations to come. Utah already provides quality care at a low cost, he added.
"Government does have a role in safety-net issues, including health care," he said, "but we don't want to make that so big we eliminate all the things the private sector can do."