With a deadline looming days away, Gov. Mark Dayton urged Minnesotans to sign up for health insurance through MNsure, saying vast improvements have been made to the state's trouble-plagued health insurance exchange.

Dayton declared Friday MNsure Enrollment Day, in the final push to get Minnesotans signed up by the national deadline of March 31. More than 152,000 people signed up through the state exchange, exceeding a revised goal set in October to help 135,000 Minnesotans acquire coverage. The total is well below the original projection of 164,000 to 270,000 enrollees.

Interim MNsure CEO Scott Leitz said that extra staff would be on hand this weekend to help with enrollment, but that more people rushing to sign up could result in longer hold times. People who encounter difficulties will be issued hold forms to ensure they were waiting in line before the deadline — similar to being in line when the polls close, he said.

Leitz said about 20 percent of MNsure enrollees are young adults, a demographic vital for subsidizing older Minnesotans who are more likely to need health care. He said MNsure didn't set a specific target for how many young people they need, but that "a strong, broad mix of people" is necessary, which will require as many younger Minnesotans as possible.

About 42,000 Minnesotans are enrolled through qualified health plans, while 110,000 are enrolled through Medicare and Medicaid.

Leitz, along with health care representatives from nine other states, was summoned Thursday to testify before Congress about MNsure's troubled rollout. In a letter to Dayton, Republican U.S. Rep. Darrell Issa and two subcommittee chairmen raised questions about the security of the health care insurance exchange and argued that MNsure "has consistently failed to deliver a usable product for its citizens."

Dayton, who said he had yet to receive Issa's letter, defended the improvements made to the program, saying success cannot be measured after just an initial enrollment period.

Locally some Republicans also criticized the program, saying that Minnesotans who lost their health plans and were forced to buy new plans on MNsure outnumbered those who were satisfied.

"We haven't heard a single proposal from the governor or the Legislature to fix the fundamental structural flaws in MNsure," said Sen. Michelle Benson, R-Ham Lake. "I would not call today a day to celebrate the successes of MNsure."

Dayton chided Republicans for criticizing the program without offering alternatives.

"Success can't be measured after this enrollment period," Dayton said. "I think after the next [fall enrollment] we'll have a better idea of the progression and maybe three years before people are aware of this program and the obligations. Changing people's behavior … takes some time. This is not going to happen overnight, it's not intended to happen overnight."