Senators and members of their staffs were exchanging stories yesterday about an episode during the trade bill debate that some called "the martyrdom of Lawton Chiles."

It happened just before midnight Wednesday as the Senate leadership was trying to work out a complex agreement to schedule final action on the massive trade bill. But Sen. Lowell P. Weicker Jr. (R-Conn.) threatened a filibuster over an amendment by Chiles that would have banned ships from U.S. ports for six months after visiting Cuba.

Chiles, a Florida Democrat, faced the choice of either pressing ahead with his Cuba amendment, which would have stalled the trade bill, or giving in and withdrawing his amendment. No other senator had been pressured to yield in such a public way to advance the trade bill.

It was an anguishing decision for Chiles, who faces election in two years from a state with a large anti-Castro Cuban population, and it showed in his face and body as he stood on the Senate floor.

Finally, he withdrew the amendment after the Democratic and Republican leadership pledged to bring it up as a free-standing resolution as soon as possible.

"This action on the part of Mr. Chiles is a demonstration of reasonableness that we too often fail to see here," said Majority Leader Robert C. Byrd (D-W.Va.) at the opening of yesterday's next-to-last-day of debate on the trade bill. Without Chiles' decision to withdraw his proposal, "this trade bill would be around here a long, long time," he said.

Republican Leader Robert Dole (Kan.) also praised Chiles and acknowledged that "it wasn't entirely fair" to force him to give up his amendment. In a pointed comment that appeared to be aimed at Weicker, Dole added: "But it's one of those unfortunate circumstances where -- if you are reasonable and want to see the Senate do its work -- then you are at a disadvantage."