American Airlines and JetBlue Airways are pushing ahead with an expansion of their partnership in the Northeast, even as a federal judge considers the government’s attempt to kill the deal.

The airlines said Friday that American will add six new routes from New York while dropping one. JetBlue will start several new routes from New York and Boston. Some will operate only during summer, and most will be limited to one or two flights a day.

American said it plans to drop service between New York’s LaGuardia Airport and Atlanta in May, when JetBlue adds that route. Delta Air Lines, Southwest Airlines and Frontier Airlines also fly the route.

American said that on May 5 it will add flights between LaGuardia and Buffalo, New York, Greenville, South Carolina, and four other cities.

The airlines' plans hinge, however, on winning a lawsuit in Boston.

The Justice Department, six states and the District of Columbia sued to kill the partnership, which lets American and JetBlue work together on setting schedules and sharing revenue on flights in New York and Boston.

The government said the deal will reduce competition and lead to higher fares, costing consumers $700 million a year. American and JetBlue argued that their combination will help consumers by making them a stronger competitor in the Northeast against Delta and United Airlines.

After a trial lasting several weeks, a judge in Boston took the case under consideration last month. A verdict is expected early next year.