Republican governors seeking to make their states enemy territory for Obamacare are facing a counteroffensive. Among the vanguard: two 74-year-old retirees walking the streets of working-class New Jersey.

Margot Lee and Claude Cesard recently went door-to-door to pitch the health law’s benefits. They’re among thousands of supporters mobilized by the nonprofit group Enroll America to encourage the uninsured to sign up for the Affordable Care Act’s new health plans, one household at a time.

The campaign is relying on tactics honed in Obama’s election victories to promote the law in states where leaders such as New Jersey Governor Chris Christie have shown little support. Low enrollment early on could deal the act a serious blow, raising costs for consumers, bolstering Republican attacks and deepening public skepticism. Success could smooth its path into the future.

“It’s a cause we believe in,” said Lee, a retired attorney, as she canvassed homes last month in Englewood, New Jersey, five miles west of New York City. “Health care in this country is a mess, and this is a step in the right direction.”

Lee got her start in political activism in 1948 at age 10, helping her grandmother hand out fliers for Harry Truman’s election. She registered voters for Obama in 2008 and 2012, and felt compelled to act this year after seeing relatives struggle without insurance, she said.

It’s her job to help counter “the big lie” being pushed by the law’s critics, Lee said.

Unfavorable Surveys

It won’t be an easy task. In June, the nonprofit Kaiser Family Foundation found 43 percent of people had an unfavorable view of the law, compared with 35 percent in support. An April survey by the group, which studies health-care policy, found 40 percent weren’t even sure the measure was still in effect

“You can’t just turn on the exchanges Oct. 1 and expect people to show up,” Thomas Buchmueller, a University of Michigan health economist, said in a telephone interview. “For a lot of people, it’s just not on their radar screen.”

Enrollment is scheduled to begin Oct. 1 through new call centers and online exchanges created by the act. As in an election, turnout will be crucial. The Obama administration has estimated about 40 percent of the new enrollees need to be young and healthy, to offset an older, sicker population expected to flood into the market. Without that balance, premiums may soar.