PORTLAND — Canadian officials are poised to initiate a bidding process for private companies interested in a renewing ferry service between Yarmouth, Nova Scotia and Portland.

Bay Ferries Ltd., which once operated The Cat, a high-speed catamaran, between the two ports has shown interest in bidding for the service, for which the province of Nova Scotia has agreed to provide a $21 million subsidy.

It’s unclear whether The Cat would return, or whether a slower vessel would be used.

Ferry service stopped three years ago when Bay Ferries, Ltd. stopped operating The Cat, which was reportedly losing $7 million a year when Province of Nova Scotia stopped subsidizing the service.

Prospective bidders met Tuesday in Halifax, Nova Scotia, to discuss conditions for an upcoming request for proposals — a move cheered by local officials here in Portland.

Mayor Michael Brennan said on Wednesday he was pleased the process is moving forward. He’s optimistic that the ferry service will be restored, since the province is committed to subsidizing operations during the start-up phase.

“It’s clear there’s going to be a strong commitment to making this happen,” Brennan said. “The history of having ferry between Portland and Nova Scotia has been a positive one. We would like to work with them to make sure this becomes a reality.”

The province is prepared to spend up to $21 million over a seven-year period to attract a long-term cruise ferry operation in Yarmouth, Nova Scotia.

A providence-appointed panel of experts issued a report in September saying that a ferry service to Maine could be viable if it provides a high-quality on-board experience, is supported by a sophisticated marketing strategy, and leverages a strong tourist experience in southwest Nova Scotia.

The panel predicted it would take an initial investment of $5 million to conduct baseline research, advertising, vessel acquisition and financing to get the service up and running. Another $13 million would be needed to repair ferry terminals in Yarmouth.

Operators will be expected to present a business plan to have a self-sustaining ferry operation once the government subsidy runs out.

Percy Paris, Nova Scotia’s Minister of Economic and Rural Development and Tourism, said the province is open to seasonal and year-round ferry services, provided the operator is focused on a giving passengers a quality, overnight experience.

“We’re leaving it in the hands of the bidders,” Percey said. “If we move forward on this whatever it is, whatever it looks like we want to make sure that it is going to be successful and it’s going to be there for the long-haul.”

Ferry service from Portland to Yarmouth began 1970, when the Prince of Fundy began operating.

The Scotia Prince ran from 1982 to 2005, when dispute over mold issues at the city-owned International Marine Terminal and declining passenger totals prompted the company to stop service. The 485-foot Scotia Prince held 1,200 passengers and promoted itself as a leisurely cruise experience, with cabins, casino games and live musical shows. A one-way trip took about 11 hours.

The Cat, which held about 775 passengers and 250 vehicles, picked up ferry service from 2006 to 2009. It made the trip in about 51/2 hours and offered passenger amenities like aircraft-style lounge seats, four movie screens, slot machines, a cafe and a duty-free shop.

The draft RFP notes that there are 70 million people within a day’s drive from Portland and 30 million people within a six-hour drive. “The northeast United States offers an enormous potential market for ferry passengers,” the RFP states.

The draft asks bidders to identify the biggest risks to a self-sustaining operation and how they plan to address them. The type of ferry service isn’t specified, but the expert panel recommended Portland as a destination since it presented the best opportunity for a cruise-style — rather than a high-speed — ferry service.

Since the loss of the ferry service, the city has become an increasingly popular cruise ship destination. In 2012, Portland hosted 59 ships with 68,773 passengers, compared with 56 ships with 85,508 passengers a year ago, according to the Port of Portland.

Jeff Monroe, a port and transportation consultant with HDR in Boston, said he was been working with two operators interested in bidding for the service — one from Italy and one from North America.

Monroe said his studies have shown that the most profitable ferry service would be an overnight cruise-style ferry that had a 24-hour turnaround. He’s optimistic the service will be restored by 2014, but only if the Yarmouth port is upgraded and operators can find a year-round use for their vessel.

“I think it has a real good chance of occurring,” said Monroe, Portland’s former transportation director.

Bay Ferries, which operated The Cat out of Portland from 2006 to 2009, is looking into whether to submit a bid, said Donald Cormier, the Prince Edward Island-based company’s vice president of operations and safety.

Cormier wouldn’t speculate about the type of ferry service the company envisioned; nor would he comment about why the company, which operated the Cat at a loss, was interested in giving it another shot.

“Until we see exactly what they want, at that point, we will evaluate whether our company will continue to participate,” said Cormier, noting the company would have to ensure profitability for its shareholders.

The Nova Scotia-based newspaper, the Chronicle Herald, reported Wednesday that the United Kingdom-based P&O Ferries, which has one of the biggest passenger and freight fleets in Europe, has also expressed interest in operating the ferry.

The paper reported that the ferry service could be up and running as soon as next year, though officials cautioned a 2014 start date is more likely.

Monroe said the state of Maine needs to view the ferry service as part if its transportation system, rather than leaving it Nova Scotia officials.

City Manager Mark Rees said the city wasn’t in a position to provide any financial incentives for a new ferry service, but stood ready to provide whatever technical assistance is needed. He noted city has made significant investments in recent years to the waterfront, building the Ocean Gateway Terminal and building a new facility at the International Marine Terminal.

Mayor Brennan said he hasn’t yet reached out to state officials, but anticipated doing so.

Percy said the province would welcome support from all levels of government in the U.S. and Canada. “It would be nice to see the state of Maine with some skin in the game,” Percy said.

Nova Scotia is expected to call for new elections this spring, which will likely add political pressure for candidates to restart the ferry service, which is seen as vital to future of southwestern Nova Scotia.

The timeline for when potential operators will need to submit their proposals had not been finalized as of Wednesday afternoon. Percy said bidders have until the end of November to submit their proposals.