The embattled director of the state's fledgling health insurance exchange resigned Tuesday amid mounting criticism of her leadership and the troubled rollout of the new health care program.

MNsure executive director April Todd-Malmlov left her $136,000-a-year post during a closed-door meeting with the program's executive committee. The board named Scott Leitz, the state's assistant commissioner of health care, to the newly created position of interim CEO while it conducts a national search for a permanent chief executive.

"MNsure must do better," Leitz said. "If there are problems or mistakes, we will acknowledge them and fix them."

Todd-Malmlov's abrupt departure comes as thousands of Minnesotans scramble to enroll in the state's online insurance marketplace by Jan. 1. The implementation of Minnesota's program has gone more smoothly than in other states, but it still has been marked by countless technical glitches, delays and frustrated consumers. State officials hope the insurance marketplace will eventually serve 1 million Minnesotans, about one in five residents.

"The recent problems some have experienced with MNsure are completely unacceptable," Gov. Mark Dayton said. "I am hopeful that this new leadership will lead to their swift resolution."

Said MNsure board Chairman Brian Beutner: "Scott has been a proven leader. We are fortunate to have someone with his capabilities and his intimate understanding of MNsure available to step in quickly and lead us through these critical next few months."

Leitz will receive the same salary as Todd-Malmlov, according to MNsure. It was not immediately known whether Todd-Malmlov received a severance package.

The success or failure of the program could have political consequences in Minnesota and nationally. Dayton, a DFLer, ensured that Minnesota was among the first to adopt President Obama's health insurance overhaul, and Republicans have been relentless in trying to tie the governor to its tumultuous rollout.

"Tonight's news offers no comfort to hardworking Minnesotans who are still unsure if they'll have insurance coverage on January 1st," said House Minority Leader Kurt Daudt, R-Crown. "For too long, Governor Dayton and Democrats have ignored the reality that their new state agency, MNsure, is failing Minnesotans."

Dayton has been one of the most vocal critics of the glitches and delays. But he has said that while Republicans are doing all they can to wreck the new health insurance program, he wants it to succeed.

The outrage over Todd-Malmlov intensified following revelations that she and state Medicaid director James Golden took a nearly two-week tropical vacation late last month, even as the program was swamped with problems.

According to Star Tribune records, the two live together and have worked closely on the implementation of the new exchange.

Todd-Malmlov did not respond to repeated requests for comment.

Leitz said his immediate priorities will be to work with health plans to make it easier for individuals to enroll in coverage and have insurance beginning Jan. 1.

Leitz, 47, brings a wealth of experience. He has been assistant commissioner of health care at the Minnesota Department of Human Services since 2011 but has spent nearly 20 years working in health care and public health. He's had responsibility for overseeing Minnesota's Medicaid program, known as Medical Assistance, and has been responsible for eligibility and benefits for MinnesotaCare, which covers low- to modest-income earners.

About two-thirds of Minnesotans using the exchange are expected to be covered by one of the two public health programs he oversaw.

Leitz also has worked at the Department of Health, where he worked on the 2008 health reform act passed under former GOP Gov. Tim Pawlenty.

Julie Brunner, executive director of the Minnesota Council of Health Plans, described Leitz as a "calm and steady leader" who doesn't get flustered under pressure.

"He's got the skills that are needed at in this point in time," she said. "And he understands that if you're going to solve a problem, you need to understand all the stakeholders' concerns around a particular issue."

Minnesota is one of 15 states and the District of Columbia building its own exchange.

The director of Maryland's exchange recently stepped down, and the head of Hawaii's health insurance marketplace announced her resignation in November, dogged by delays and low initial enrollment.

The leader of Oregon's health exchange took a medical leave earlier this month as state officials were reviewing his job performance because of delays with the enrollment system.

Before MNsure's launch, its officials faced an unnerving data security breach involving more than 1,000 Social Security numbers. MNsure also endured criticism over its multimillion-dollar advertising campaign.

In addition, MNsure was chided for not casting a diverse enough net when doling out $4 million in federal grants to help difficult-to-reach communities, such as African-Americans and those with mental health issues. Todd-Malmlov admitted problems with the screening process, and the board ended up freeing up additional money for a second round of grants.

Staff writer Abby Simons contributed to this report. baird.helgeson@startribune.com 651-925-5044 jackie.crosby@startribune.com 612-673-7335