An aggressive regional airline is vying with real estate developer Donald Trump to buy Eastern Airlines' Northeast shuttle service.

America West Airlines, the nation's 10th largest carrier, has put a competing offer for Eastern's three-city shuttle on the table, sources close to the situation said late Wednesday.Meanwhile, takeover strategist and TWA owner Carl Icahn and outgoing baseball Commissioner Peter V. Ueberroth are gaining momentum as the top contenders for the rest of strikebound Eastern, sources said, speaking on condition of anonymity.

Observers believe the airline's fate could be decided when the directors of Eastern's parent company, Texas Air Corp., meet Thursday in Houston.

Texas Air Chairman Frank Lor-enzo and Trump were nearing agreement Wednesday on the sale of the shuttle, said a spokesman for the Trump organization.

Trump agreed in October to buy the shuttle from Eastern for $365 million. But he recently told Texas Air that the strike against Eastern, in its fourth week, had lowered the shuttle's value and that he would reduce his offer by about $125 million.

Texas Air countered by telling Trump it would look for other buyers of the service, which links New York with Boston and Washington with hourly flights.

Under terms of the America West offer, current employees of Eastern would be excluded from working for the shuttle after it was sold to the Phoenix-based carrier, the sources said.

Trump, on the other hand, has recognized Eastern's unions as valid bargaining representatives for future shuttle employees. He has said he plans to negotiate separate agreements with them.

America West is mainly interested in the shuttle's landing slots in the three cities and in purchasing Boeing 757s from Eastern to augment its fleet, the sources said. Trump's agreement with Texas Air calls for him to buy 17 smaller and older Boeing 727s, but the sources noted that none of those planes is specifically attached to the shuttle service.

A spokeswoman for America West declined late Wednesday to directly confirm the airline's interest in the shuttle.

America West turned a $45 million loss in 1987 into a profit of $9.4 million last year.