The fashion gurus signed a £1.2 million "golden handcuffs" deal with ITV after defecting from the BBC in 2005. They had previously fronted What Not To Wear for five years.
Their latest show, Trinny and Susannah Undress The Nation, has pulled in disappointing audience figures for ITV1 in recent weeks. The programme dropped to an all-time low of 2.18m in the 9pm slot last Tuesday.
"The show has been a huge disappointment," the Daily Mail quotes an ITV source as saying. "They paid a lot to bring them over, but they won't be renewing the current deal."
However, an ITV spokesman insisted: "Trinny and Susannah are an important part of the ITV family. As well as the series which is currently on air, they return in the autumn with a third series of Undress The Nation."
A representative for the pair confirmed that a decision on whether to renew the ITV deal would be made within the next few months.