It is 61 years after Walter Williams and Eddie Levert first formed a band, and the surviving founder members of the O’Jays can’t seem to decide whether or not they are about to split up. Their new album is called The Last Word, and at nearly 77, Levert thinks it is time to retire. “It’s like the body is saying to me: ‘You don’t need to do that strenuous choreography any more!’” he says, from his home in Las Vegas. “My knees are telling me they can’t take it.”

Calling from his home, also in Vegas, Williams isn’t so sure. “Probably age-wise it should be,” he offers, “but the desire to continue what we started could go on another two or three years. If we’re still happy and God continues his blessings on us, I think we might be still around.”

If it is their final album, The Last Word seems like a good way to bow out – a smart updating of the sound that made the O’Jays prime exponents of the celebrated orchestrated soul sound minted by Philadelphia International Records – but it would bring to a conclusion one of the most extraordinary careers in soul. By rights, they should have split up 47 years ago, before the singles Backstabbers and Love Train put them at the top of the charts, worn down by a 14-year career without a big hit. Along the way, they had tried everything, from relocating to California to make “beach music” for a primarily white audience (“playing with the Dave Clark Five and Sonny & Cher”) to chancing their arm in Detroit: they turned down a deal with Motown, opting instead for Berry Gordy’s ex-wife’s label Thelma, and found themselves living in a boarding house filled with future stars. “Wilson Pickett, Martha Reeves and the Vandellas, Edwin Starr, the Temptations,” remembers Levert. “All struggling artists trying to get a break. We watched them all get successful and we’re sitting back up there: ‘When’s our turn?’ It was a very stressful time.”

Philadelphia International’s bosses Kenneth Gamble and Leon Huff spotted the band at Harlem’s Apollo Theater, supporting an act they were working with called the Intruders. “They just pounced on our background in gospel,” says Williams. “My dad was the choir director at St Mark Baptist Church in Canton, Ohio and Eddie and I sang in the choir. They saw and were able to capitalise on that sound.”

Philadelphia International was a tough environment – “We would spend six months up there, rehearsing the songs every day until we knew them backwards,” says Levert, “until we knew how to sing them from the soul and the heart. We’d record an album in one day, 12 songs: start at eight in the morning, be done by 10 or midnight” – and among its artists, competition for the best songs from the label’s team of writers was ferocious. “Especially with the stuff they gave Teddy Pendergrass and Harold Melvin & the Blue Notes,” laughs Levert.

Still, the O’Jays scored a string of impermeable hits – the much-sampled For the Love of Money, plus Give the People What They Want and I Love Music – and hired Motown’s famously fierce choreographer Cholly Atkins to give them the edge over their competitors at the label. “He would rehearse us seven days a week, eight hours a day; we were with him years before we got Sundays off,” says Williams. “And that helped us to be devastating to all the other groups, even the Motown groups, we had to beat them. Not a brag,” he adds. “Just the truth!”

The military precision of Philadelphia International didn’t preclude the O’Jays experimenting. They followed their 1972 breakthrough with Ship Ahoy, a concept album about slavery, which they performed live dressed in rags and chains. The title track apparently still has the power to cause consternation. “We actually had to take that song out of the set a couple of months ago, because it seemed to have offended people,” says Williams. “Even black people were shocked. A black writer from Alabama really blasted us for performing Ship Ahoy – it’s just a friendly reminder of where we came from, saying we should not go back to those days.”

The O’Jays’ penchant for social comment makes it all the more surprising that they number among their fans one Donald Trump, who first used For the Love of Money as the theme to The Apprentice – “I don’t think he really listened to the lyrics,” laughs Levert – and then attempted to use Love Train for his election rallies. “Yeah, he wanted to change the words to Trump Train,” sighs Williams. “We had to send him a cease-and-desist letter.”

Moreover, he has become the subject of The Last Word’s standout track, Above the Law. “We’ve always spoken about truthful things,” says Williams. “At one point we were called Gamble and Huff’s messengers, and that’s not such a bad title to wear. Tell the truth, put a beat to it so people can enjoy listening and feel the groove and understand. So if you wasn’t aware,” he laughs, “now you’re aware.” And off he goes, possibly into retirement, possibly not.

The Last Word is out now