On a day when Jack Kent Cooke, Redskin owner, strongly endorsed the club's stand in the John Riggins holdout situation, team sources revealed that Riggins has as much as $800,000 coming to him in deferred contract payments.

According to the sources, the deferred money, held back from the $300,000-a-year salary the Redskins have paid Riggins the last four seasons, is one reason he could retire.

Riggins is home in Lawrence, Kan. He refuses to report until the Redskins guarantee the option year -- next season -- of his contract, paying him $300,000 whether he plays or not in 1981.

Cooke, here to watch Washington scrimmage the Colts, said he completely supported Bobby Beathard, general manager, who has refused to negotiate with Riggins.

Cooke said he has refused to deal with players in similar contract situations since becoming a team owner. He is convinced it is the correct policy.

A team source said that the longer Riggins holds out, the more adamant it appears both Cooke and Beathard will become. "And despite what they say," said the source, "Riggins really is talking about renegotiation. The option year is part of his original contract. He wants it changed. That's renegotiating and the Redskins just aren't going to start renegotiating.

"If you start with one player, where does it end?"