PORTLAND – New England’s largest grocer is preparing to expand into Maine, setting the stage for fresh competition for the state’s food dollar.

Stop & Shop, a Quincy, Mass.-based unit of Ahold USA, has one store close to receiving town approval in Kennebunk and another moving through the approval process in Portland.

Stop & Shop’s entry in the Maine market would provide a new rival for Hannaford and Shaw’s, two companies with roots in Portland that dominate the grocery market in Maine.

In recent years, discounter Wal-Mart has taken some of the business, expanding some of its general-merchandise stores into supercenters equipped with full grocery sections.

The arrival of Stop & Shop is likely to further shake up the industry, which has quickly become a world of intense competition and razor-thin profit margins.

“Shoppers are going to get quite a variety,” said Mike Berger, editor of The Griffin Report, which tracks the supermarket industry. “I see a very competitive market.”

Some of the local concern over Stop & Shop stores relates to their size. Although they are smaller than “big box” stores, such as Wal-Mart and Home Depot, Stop & Shop locations tend toward the large end for supermarkets, at 65,000 square feet and up.

Most Stop & Shops have more than two dozen departments, and the company has partnerships with retailers such as Dunkin’ Donuts and Office Depot that create stores within the stores.

Store size and features are dictated by the community, said spokeswoman Faith Weiner, noting that the company has a number of layout models it can use to tailor stores to particular communities.

Stop & Shop is the market leader in Connecticut and also has scores of stores in Rhode Island, New York, New Jersey and Massachusetts. It moved into New Hampshire last year and hopes to have at least two stores open in Maine next year.

Weiner declined to outline the company’s long-term plans for the state, although another Stop & Shop official recently indicated it likely will expand at the same clip it is expected to adopt in New Hampshire, where it envisions five new stores a year for several years.

Stop & Shop will face entrenched competitors when it starts operating in Maine. Hannaford, with 46 stores statewide, has 46 percent of the grocery market, according to a survey by The Griffin Report released last summer. Shaw’s, which has 20 stores in the state, captured just over 20 percent, and Wal-Mart had 10 percent.

Weiner said Stop & Shop is prepared to compete for its share and isn’t making a move into Maine simply because it’s the next logical geographic step.

“We have a plan that we’re pulling together,” she said. “We obviously, as a company, have made a decision that there’s room for us in Maine. We’ve done that through research and other consumer information.”