The longest losing streak in the history of the Triple Crown will be on the line when trainer Johny Campo enters Hey Hey J.P. Thursday in Saturday's Belmont Stakes.

Campo is 0 for 19 in the Kentucky Derby, Preakness and Belmont since making his debut in the prestigious series in 1971 with Jim French.

The colorful conditioner has saddled a dozen 3-year-olds in the three events and has come close to victory only once, in the 1971 Belmont, when the 34-to-1 Pass Catcher tried valiantly to lose by walking the last 16th of a mile of the mile and a half race - only to triumph by three quarters of a length over Jim French after having led by five lengths at the eighth pole.

The 19 starters Campo has sent to the post have lost the three classics by a grand total of 362 lengths, or slightly better than a 19-length average. Hey Hey J.P. is in the tradition, having finished 23 1/2 lengths behind Seattle Slew in the Preakness before finishing third in the Jersey Derby on Memorial Day at 97 to 1.

The high point of Campo's traipsing through the Triple Crown may have occurred in 1973 when Twice A Prince lost by 31 lengths but finished second to Secretariat and earned $33,044.

Jim French ran second, third and second in the three 1971 contests. Good Behaving and Play The Red are the only other Campo charges to have been taken seriously by the bettors, at shorter than 5-to-1 odds. Good Behaving finished 11th in the 1971 Belmont. Play The Red wound up sixth at Belmont last spring after having closed fairly well to second to Elocutionist at Pimlico.

Hey Hey J.P. will not threaten Seattle Slew for favortism Saturday. The dark bay colt sired by Wig Out figures to be the second longest or the longest shot on the board - behind Slew, Sanhedrin, Run Dusty Run, Iron Constitution and Spirit Level. Mr. Red Wing is the only colt he has a chance of beating in the parimutuels, at about 70 to 1.

There are those who claim Campo has made the high camp of the classics by repeatedly sending such longshots into situations where they were overmatched.

The trainer can summon two immediate defenses for his actions. First, his horses have finished ahead of such outstanding runners as Canonero II, Sham, Bold Forbes and Honest Pleasure somewhere along the Triple Crown trail.

Secondary, but more important, Campo's horses have earned $138,871 from their 19 appearances.

Hey Hey J.P. did not appear to belong in such exalted company until the Jersey Derby, when he probably surprised his trainer by finishing within a nose of Iron Constitution for second money. Cormorant won the mile and an eight contest by 3 1/2 lengths.Until then, Hey, Hey J. P.'s best efforts were over sprint distances.

Certainly the colt bred in Florida by Campo - the trainer owns the dam, Nat E. Shu, by John William - and owned by the Fast Piarina Stable will not be short of experience Saturday. He has run 24 times, twice as much as most of the Belmont competition except for Iron Costitution, which will be making his seventh start in eight weeks.

Perhaps the bottom line regarding Campo and the Triple Crown is that the rotund trainer who began his career in 1968 regards the events as merely three more opportunities to make the money by getting part of the rich pruses. His stable earns more than $1 million each season. Hey Hey J. P. already has more than $113,000 in his bank account.

So, from Campo's standpoint, who cares if he is about to become 0 for 20 in American's most famous horse races. He might even scratch Hey Hey J. P. from the Belmont on Friday or Saturday morning if Seattle Slew stays sound.

Besides, someone has to be last, Campo knows, having seen his horses finish there before when Prince Fauquier, Syllabus, Torsion and Media brought up the rear in, Triple Crown contests.