Undated (AP) _ Here are Sunday's developments on the presidential campaign trail:

THE CANDIDATES:

-GEORGE BUSH: Vowed to increase U.S. pressure on Cuba to abandon communism. Fidel Castro ''will fall of his own weight,'' Bush said in an interview with a Spanish-language TV show released Sunday.

-BILL CLINTON: Endorsed the free-trade treaty with Mexico, but said he would not sign it unless additional steps were taken to protect American workers. ''If it is done right, it will create jobs in the United States and in Mexico,'' he said during a speech in Raleigh, N.C.

-ROSS PEROT: Remained under wraps on his first weekend after announcing his candidacy. Aide Sharon Holman said Perot's first ad, a 60- or 90-second campaign spot, was likely to air Monday night during the Dallas Cowboys- Philadelphia Eagles game on ABC.

NEWS OF NOTE

-Perot came in 19th on Forbes magazine's annual list of the richest Americans. His net worth was estimated at $2.4 billion, up from the magazine's estimate of $2.2 billion last year.

ENDORSEMENTS:

-Clinton: Detroit Free Press; The Seattle Times.

UPCOMING ON TV:

-Clinton and Gore appear on CNN's ''Larry King Live'' Monday night at 9 p.m. EDT for a live 90-minute interview.

MONDAY'S STOPS:

-BUSH: Dover, Del.

-CLINTON: Florida bus tour, including stops in Daytona Beach, Orlando and Ocala.

-PEROT: Dallas.

-QUAYLE: Tacoma, Wash.; Palo Alto, Calif., San Francisco.

-GORE: Florida bus tour with Clinton.

-JAMES STOCKDALE. Unavailable.

FOUR YEARS AGO TODAY:

-Michael Dukakis promised a vigorous sprint to the Election-Day finish line, saying ''we have five, long, tough aggressive weeks to go and believe me we'll be tough and aggressive.'' Bush pushed proposals to improve school programs and environmental issues, saying youngsters need ''a family that functions and an environment that motivates.''