PORTLAND, Maine — City leaders are welcoming a developer’s early plan for a 23-story building in Portland’s Old Port, making the case that it would boost urban density and help catalyze economic growth.

But skeptics argue the residential building would be ill-placed and open the door to more development that they worry would change the character of the city.

Tim Soley, president of East Brown Cow Management, has been meeting informally with Portland’s city planning department over the past year about the possibility of putting up Maine’s tallest building on a lot the company owns downtown. The building has not been officially proposed to the city, but the developer is eyeing a lot north of the Hyatt Place hotel — itself, one of East Brown Cow’s 16 downtown properties.

And some city officials who previously were aware of Soley’s ambitions say the plan has merit.

“I think what he’s trying to do in terms of creating an urban center is the right thing,” said Mayor Ethan Strimling, who received more than $1,000 in campaign donations from Soley and an East Brown Cow subsidiary. “I’m in favor of increased density on the peninsula, especially downtown, and the best way to do it is to go up.”

The mayor said the buildings should be judged on a case-by-case basis, noting concerns with another early-stage proposal for condominiums on Sheridan Street. But he generally favors vertical growth in the downtown and along Portland’s major traffic corridors, he said.

There is an obvious need for more housing stock in the city, Strimling said — though he does not believe Portland’s housing problems can be solved by development alone.

One advantage of the greater population density allowed by tall buildings is a broadening of the city’s tax base, said Portland Chamber of Commerce President Christopher Hall. Tall residential buildings that ease the housing crunch also could help bolster the city’s workforce, Hall claimed.

But Tim Paradis, who led opposition to the Midtown development that resulted in the project being dramatically cut back, said Soley’s idea is the wrong type of development for Portland and would open the door to unprecedented vertical growth.

“I would imagine if Portland started putting mini-skyscrapers all over the place it would damage our brand. It would damage the reasons people come here to visit, and it does not have to happen,” Paradis said.

If built, the Soley building might throw long shadows over parts of downtown and affect wind in area, Paradis worried. And he would prefer to see tall buildings put up on the ridge of the Portland peninsula, “without extreme changes in our traditional zoning.”

Even 20 feet below Congress Street, the East Brown Cow building would likely rise above City Hall. And the proposal surpasses height regulations in that part of downtown by more than 100 feet.

But Portland is re-evaluating height limits as it develops a new comprehensive plan for city growth. And asked about the present caps in that area, the city’s head urban planner, Jeff Levine, said changes may be recommended.

“I’m not wedded to these numbers,” he said.