An "American Idol" reject who volunteered at a Brooklyn elementary school was arrested for sending sexually suggestive text messages to a 12-year-old boy, authorities said Wednesday.

Colin Leahy - who compared himself to singer Clay Aiken during an embarrassing tryout for the hit TV show - also discussed oral sex with two 10-year-old students, authorities said.

Special schools investigator Richard Condon said the 23-year-old was charged with two counts of child endangerment for his allegedly inappropriate behavior with students at Public School 236 in Mill Basin.

In 2003, Leahy was briskly booted from the third season of "American Idol." His poor performance and humiliating rejection were broadcast on the program.

Leahy described himself in the audition as being just like Aiken, the runnerup in the second season.

"What I have in common with Clay is that I'm also a camp counselor," Leahy said. "I like to make people happy and smile."

His audition did anything but.

The judges panned Leahy's rendition of the American Juniors song "One Step Closer."

"This is just about as bad as it can possibly get," judge Simon Cowell told Leahy. "I can't think of anything I've actually hated more."

Leahy shot back, accusing Cowell of having a fake British accent and saying, "He needs to lose it and find a real job."

Leahy, who could not be reached for comment, was hired last year as a substitute paraprofessional at PS 236, a city Education Department spokeswoman said. His position was later cut, and he became a volunteer at the school through Learning Leaders, a nonprofit group.

Leahy, who has no prior arrest record, had been screened and fingerprinted before working at the school. He was removed when the text message probe began, the spokeswoman said.

He sent more than 29 messages on Nov. 2 to a 12-year-old student, questioning the boy about whether he's gay, investigators said. The boy told investigators that the messages made him uncomfortable.

Leahy allegedly told investigators he was "just curious" about whether the student was gay. He admitted he had discussed oral sex with two 10-year-olds but said he was only "joking," investigators said.

The students said Leahy never molested them, but one said Leahy had accidentally punched him between the legs when they went to see a movie together.