Jack Jones, a prolific nightclub singer whom Frank Sinatra once called the “next major star of show business,” has died at age 86.

Jones died Wednesday night at Eisenhower Health in Rancho Mirage after a two-year battle with leukemia, his manager Milt Suchin confirmed Thursday to The Times. Suchin said that Jones “passed peacefully holding hands with his wife Eleonora and his beloved toy poodle, Ivy.”

The Grammy-winning baritone, who released more than 50 albums during his career, is best known for performing the theme song for the ABC sitcom “The Love Boat,” which ran for nine seasons, from 1977 to 1986. Originally released as a single in 1979, with a cover of Barry Manilow’s “Ready to Take a Chance Again” on the B-side, Jones’ disco-esque tune has been covered by entertainers including Charo and Olivia Newton-John.

Also an actor, Jones’ credits included “Juke Box Rhythm” in 1959, the 1978 horror film “The Comeback,” and the 2002 TV movie “Cruise of the Gods.” He even made a cameo as a nightclub singer in the 2013 film “American Hustle.”

Once pegged as an heir to Frank Sinatra, Jones was described by Ol’ Blue Eyes himself as “the best potential singer in the business. He has a distinction, an all-round quality that puts him potentially about three lengths in front of the other guys.”

In addition to two Grammys, Jones has been honored with stars on the Palm Springs Walk of Stars and the Hollywood Walk of Fame.

John Allan Jones was born Jan. 14, 1938, in Hollywood to singer Allan Jones and Emmy-nominated actress Irene Harvey. It was the same day his father recorded his hit “Donkey Serenade,” which appeared in the 1937 film musical “The Firefly,” co-starring the elder Jones, according to Jones’ website.

Jones attended University High School in West L.A. while studying drama and singing with private teachers hired by his father. Among the fondest of his high school memories was the day his friend Nancy Sinatra invited her father to sing in their school auditorium. The experience solidified Jones’ aspirations to become a professional singer.

Weeks after his 1957 high school graduation, Jones made his professional debut as part of his father’s act, first in Elko, Nev., and then at Las Vegas’ Thunderbird Hotel. He went solo shortly thereafter.

His first break came when a demo he recorded for songwriter Don Raye found its way to Capitol Records, which signed the newcomer in 1959. There, he released his debut album, “This Love of Mine,” the Desert Sun reported.

Following creative differences with the legacy label, Jones moved to Kapp Records, where he released his first hit single, “Lollipops and Roses,” in 1961, the outlet reported. The track won him his first Grammy Award in 1962 for best solo vocal performance.

Jones was still working at his “day job” as a gas station attendant when he released his first album with Kapp, and was delighted when one day, while washing a customer’s windshield, he heard his song playing on the radio. He went on to release 19 albums with Kapp Records and later nabbed another Grammy, for his 1963 single “Wives and Lovers” — which rose to No. 14 on Billboard’s Hot 100.

Kapp “put the tune on the B-side of the single,” Jones told The Times in 1993, “but disc jockeys turned it over and played it anyway.”

After the song garnered criticism for its “politically incorrect” themes, Jones told The Times he replaced the lyrics “Hey little girl, do your hair, fix your makeup” with the alternative lines “Hey, little boy, cap your teeth, fix your hairpiece.”

By the end of the 1960s, Jones had moved to RCA Victor and transitioned into a more contemporary sound. His album “A Time for Us” (1969) features covers of renowned songwriters including Randy Newman, Carole King and Gilbert O’Sullivan.

Dropping his smoking habit in 1980, Jones kept control of his smooth singing voice well into his 80s and made regular appearances in casino nightclubs, the Washington Post reported.

A resident of Coachella Valley for the last several decades, Jones received a star on the Palm Springs Walk of Stars in 2003. Celebrating his 80th birthday at Palm Desert’s McCallum Theatre in 2018, he quipped that, because many of his singing “rivals” were deceased, his ambition was “to be the world’s greatest singer by default,” the Desert Sun reported.

Jones is survived by his wife Eleonora Donata Peters and stepdaughters Nicole Whitty and Colette Peters; his daughter Crystal Thomas, from his marriage to Katie Lee Nuckols; daughter Nicole Ramasco, from his marriage to Kim Ely; and three grandchildren.