NEW YORK (AP) — Bobby Hart, an influential figure in the Monkees’ multimedia success, known for writing hits like “Last Train to Clarksville” and “I’m Not Your Steppin’ Stone” alongside Tommy Boyce, has passed away at 86.

Hart passed at his residence in Los Angeles, as confirmed by Glenn Ballantyne, his friend and co-author. His health had been declining since a hip fracture last year.

During the mid-1960s, Boyce and Hart were a winning duo, most notably for their work with the Monkees, a television-based group promoted by Don Kirshner. The pair crafted the Monkees’ iconic theme tune, famous for its introduction, “Here we come, walkin’ down the street,” along with the catchy, “Hey, hey, we’re the Monkees.” They also penned “Last Train to Clarksville,” the group’s first chart-topping single. The Monkees’ self-titled, multi-million-selling debut album featured six songs from Boyce and Hart, who also produced and enlisted their backing group, the Candy Store Prophets, for sessions.

“I attribute much of our major success to them,” wrote Micky Dolenz of the Monkees in the introduction to Hart’s 2015 memoir, “Psychedelic Bubblegum,” crediting Boyce and Hart for not only writing significant hits but for crafting the distinct Monkee sound as producers.

As their popularity rose and the Monkees began steering their artistic direction, Boyce and Hart ventured into their own paths. They released albums like “Test Patterns” and “I Wonder What She’s Doing Tonite,” and appeared on TV shows such as “I Dream of Jeannie” and “Bewitched.” Politically engaged, they supported Robert F. Kennedy’s 1968 presidential campaign and penned “L.U.V. (Let Us Vote)” in favor of the 26th Amendment, which in 1971 lowered the voting age to 18. Their repertoire also included “I Wanna Be Free” for the Monkees and the theme for the soap opera “Days of Our Lives.”

They were covered by everyone from Dean Martin (“Little Lovely One”) to the Sex Pistols (“I’m Not Your Steppin’ Stone”).

In the ensuing decades, Hart achieved further success with different collaborators. He composed for the Partridge Family and co-wrote “Over You” with Austin Roberts, performed by Betty Buckley in “Tender Mercies” and earning an Oscar nomination. Partnering with Dick Eastman, he wrote “My Secret (Didja Gitit Yet?)” for New Edition. Hart and Bryce toured alongside Micky Dolenz and fellow Monkee Davy Jones in the ’70s, producing “Dolenz, Jones, Boyce & Hart,” and enjoyed renewed interest during the Monkees’ revival in the 1980s.

Boyce, who died in 1994, and Hart were the subjects of a 2014 documentary “The Guys Who Wrote ‘Em.” Hart was married twice, most recently to singer Mary Ann Hart, and had two children from his first marriage.

He was a minister’s son, born Robert Luke Harshman in Phoenix, Arizona. In his memoir, he remembered himself as a shy kid with a “strong desire to distinguish” himself, as he wrote in “Psychedelic Bubblegum.” Music was the answer. By high school, he had learned piano, guitar and the Hammond B-3 organ. He also started his own amateur radio station, eventually adding a console, turntables and microphones. After graduating from high school and serving in the Army reserves, he settled in Los Angeles in the late 1950s, hoping first to become a disc jockey, but soon working as a songwriter and session musician. His name shortened to Bobby Hart, he toured as a member of Teddy Randazzo and the Dazzlers, and with Randazzo and Bobby Weinstein wrote “Hurt So Bad,” a hit for Little Anthony and the Imperials later covered by Linda Ronstadt.

He also befriended Boyce, a singer and songwriter from Charlottesville, Virginia, with a “very unusual personality, spontaneous and extroverted, yet very cool at the same time.” Boyce and Hart helped write the top 10 hit “Come a Little Bit Closer” for Jay and the Americans and were a strong enough combination that Kirshner recruited them for his Screen Gems songwriting factory: They were assigned to the Monkees. Asked to come up with songs for a quartet openly modeled on the Beatles, they devised a twangy guitar line similar to the one for “Paperback Writer” and wrote “Last Train to Clarksville,” a chart topper in 1966. When Kirshner suggested a song with a girl’s name in the title, they turned out “Valleri” and reached the top 5.

For the show’s theme song, a stroll outside was enough.

“Boyce began strumming his guitar and I joined in by snapping my fingers & making noises with my mouth that simulated an open & closed hi-hat cymbal,” Hart wrote in his memoir. “We had created the perfect recipe for inspiration and started singing about just what we were doing: ‘Walkin’ down the street.'”