PORTLAND – The arrival of a low-cost airline, prospects for growth and growing security requirements have led officials to push to break ground as early as late next year on the first phase of a new terminal at the Portland International Jetport.

The project, which will be presented to a city committee next week, could nearly double the size of the current facility by the end of the decade.

City officials hope that a bigger terminal and new carriers will strengthen the local economy as well as reduce the number of passengers siphoned away by competing airports in Boston and Manchester, N.H.

“For business to expand, we need frequent flights and low-priced flights, so people don’t have to go to Manchester or Boston to make connections,” said James Cohen, a city councilor who chairs the transportation committee.

It’s premature to know how the committee or the full City Council will react to the proposal, Cohen said, but growing activity at the jetport is encouraging.

The airport has made nearly $70 million in improvements in recent years with additional parking and upgraded runways. Even so, the city has continued to lose traffic to Manchester and Boston, which have more frequent flights and an assortment of low-cost airlines. Those options attract both leisure and business travelers from southern Maine.

Roughly 340,000 Maine residents flew out of Manchester last year, according to airport surveys. That’s only 10 percent of the total traffic there but more than a quarter of the 1.2 million or so passengers who went through the Portland airport in 2002.

The number of travelers using the airport appears to be on the rise. In February, for example, it set a record for passengers with 86,699 people boarding flights from Portland, an increase of 4,534 from the same month last year.

But Manchester has been growing much faster. Boardings there went from 1.1 million in 1997 to 3.4 million in 2002. A $500 million expansion under way there – including a 30 percent increase in terminal space – will allow it to handle more than 5 million passengers.

Portland officials hope pending developments allow the airport to hold its own. “Our goal is to be the airport of choice for southern Maine,” said Jeff Monroe, Portland’s transportation director.

Driving much of the interest in Portland is a new breed of discount carriers that use smaller jets to serve secondary, regional markets.

In addition to the arrival of Independence Air, which kicked off its low-cost service to Portland on Wednesday, the jetport is optimistic about attracting other carriers, Monroe said.

One of them, JetBlue Airways, has announced plans to buy a fleet of Embraer 190 aircraft, which seat 100 passengers. The first planes are to be delivered next year. Monroe said the carrier wants to be flying some of those planes into Portland in 2006 but hasn’t made a definite commitment.