NASHVILLE (AP) - TennCare Director Darin Gordon, who spearheaded Republican Gov. Bill Haslam's unsuccessful Insure Tennessee proposal, announced Wednesday that he is stepping down after 10 years in charge of the state's expanded Medicaid program.

Haslam credited Gordon, who will retire in June, with helping to stabilize the TennCare program after it had seen 10 directors come and go in the 12 previous years. The $10.5 billion TennCare program covers 1.5 million people, or about one in every five Tennesseans.

TennCare makes up nearly one-third of the state's annual budget, and spiraling costs led then-Gov. Phil Bredesen, a Democrat, to cut 170,000 people from TennCare rolls in 2005. Gordon worked to rein in costs both as director and in his previous TennCare positions as the head of managed care programs and as chief financial officer.

Gordon last year served as Haslam's chief liaison to the Legislature on the proposal to extend health coverage to 280,000 low-income Tennesseans. Gordon tried to persuade skeptical Republican lawmakers to approve the plan that would have drawn down $2.8 billion in federal Medicaid money over the course of the two-year pilot program. State hospitals had agreed to cover the state's entire $74 million share, and Gordon said the state had the authority to withdraw if costs exceeded projections dating back to the 2005 enrollment cuts.

But GOP lawmakers defeated the Insure Tennessee plan amid worries that it was too closely linked to President Barack Obama's signature health care law.

"Darin was one of the primary architects of Insure Tennessee, working with the different people he knows and respects out of that business," Haslam said. "So we'll miss his expertise."

Gordon told reporters Wednesday that the thwarted Medicaid expansion didn't play into his decision to retire.

"Obviously I would have hoped - and I still expect someday we'll have some kind of s olution for that problem - and I would have liked to have been able to bring that to market," he said. "But it had no bearing on it whatsoever."

Haslam he hopes to announce the next TennCare director before the Legislature adjourns next month.

Health care advocates have been turning up the pressure on House Speaker Beth Harwell, R-Nashville, and other lawmakers for rejecting the Insure Tennessee proposal, buying space on 20 billboards around the state to draw attention to the issue.

Martha Ingram, a Nashville philanthropist and one of the state's wealthiest citizens, said she got involved because she thought lawmakers were not fulfilling their responsibilities to citizens.

"I honestly don't really know how they sleep at night," Ingram said in a recent conference call.

Haslam said it was unfair to single out Harwell, because she doesn't have the power to bring the measure straight to a House floor vote.

"When you talk about what are you goin g to do about it, you ought to come up with things that are realistic prescriptions for what we can do," he said.