AUGUSTA — When enrollment in health care exchange reopens Saturday, the Maine groups that will encourage the uninsured to sign up say they have a powerful resource: the voices of the tens of thousands of residents who have already enrolled.

The first open sign-up period for the Affordable Care Act brought out those who were motivated to get coverage because perhaps they had lost theirs or faced an illness. But finding those who remain uninsured – whether by choice or by a lack of knowledge – will prove more difficult this time around, health advocates say.

The stories of the newly insured may be the way to attract those hard-to-reach segments of the population.

“One of the most powerful things is to hear from someone who lives in your area and looks like you saying, ‘I got a good deal, and I’m covered, and I feel better,'” said Wendy Wolf, president and CEO of the Maine Health Access Foundation. The group is launching a $500,000 marketing campaign targeting those who signed up last time and need to re-examine their options and those who remain without coverage.

Television ads featuring testimonials from people across the state who bought coverage on the exchange will emphasize that 90 percent of Mainers who signed up received a tax credit to help pay for their plans. Wolf’s group will also run online ads and plaster posters on the side of buses in Portland and Lewiston.

More than 35,000 residents in Maine, one of 36 states relying on the federal health care exchange, gained coverage under the health care law, according to a Gallup poll released in August. The poll indicated that the rate of uninsured people dropped from about 16 percent last year – or roughly 209,300 people – to slightly more than 13 percent through midyear 2014 – or about 172,900 Mainers. The state’s Bureau of Insurance does not keep track of how many residents are uninsured.

Emily Brostek, executive director of Consumers for Affordable Health Care, said many of those who didn’t get coverage during the last open enrollment period were unaware of the options available to help them pay for it.

“There’s a real knowledge gap,” said Brostek, whose organization runs a helpline for people seeking health care. “It’s not the case that they weren’t interested. They just assumed they couldn’t afford it.”

Because Maine didn’t expand Medicaid under the heath care law, an estimated 24,000 residents have fallen into a gap where they don’t qualify for Medicaid coverage or tax credits to help them buy private insurance, possibly putting the plans out of reach for some.

Another potential motivator to get coverage this time around will be bigger penalties. A person who didn’t have coverage last year had to pay either 1 percent of his household’s adjusted gross income or $95, whichever is greater. This year, an uninsured person will have to pay 2 percent of household income or $325.

Jake Grindle, the head navigator with Western Maine Community Action who’s leading a team of about 75 “navigators” across the state, said they plan to attend as many public events as possible and “talk wherever people will listen” to capture those who haven’t yet signed up for coverage.

But they’re also relying on those whom they helped enroll successfully last time to spread the word.

“One of the biggest strengths that I think we’re going to have is the word of mouth from the really impressive amount of people that we did manage to reach last year,” Grindle said.