A Teamsters official threatened on Saturday to expand the Eastern Airlines strike to rival Pan American, while union leaders discussed ways for employees to buy both carriers in "the opportunity of a lifetime."

Eastern employees rallied in Washington, New Jersey and New York, where Gov. Mario Cuomo threw his support behind the workers and challenged President Bush to intervene in the labor war with Eastern boss Frank Lorenzo.Eastern's 8,500 machinists entered their third week on strike, which has crippled the nation's seventh-largest airline and forced it to seek bankruptcy protection. The workers have refused to give wage concessions.

And a Teamsters official warned that the strike could be expanded to struggling Pan Am, which competes with Eastern on the Boston-New York-Washington shuttle route.

"The strike at Eastern Airlines is a fight for every working person in the United States," said William F. Genoese, director of the Teamsters Air Division.

Federal judges have restrained other unions from sympathy strikes that could have extended to the nation's railways and other airlines. But Genoese said a Pan Am strike would be legal because its 4,200 Teamsters have an open contract and other unions could honor their picket lines as pilots and flight attendants have done at Eastern.

Meanwhile, rallies in Washington, New York and Newark launched the third week of the walkout.

A crowd estimated by police at more than 1,000 turned out for a rousing, flag-waving rally at New York's LaGuardia Airport. Gov. Mario Cuomo, wearing a black satin pilot's jacket and a pilot's cap, challenged President Bush to intervene in the labor war with Lorenzo.

"Focus your thousand points of light on this situation. It's time to lead, Mr. President," he said.

In Washington, about 300 people gathered across the street from the White House to hear similar remarks aimed at Bush, who was reported to be relaxing on the White House grounds playing horseshoes and tennis.