Trending Topics, which is expected to air on ITV, was announced by Ross on his Twitter page last month.
Walliams has now been linked to the show after taking part in rehearsals, The Sun reports.
Andi Osho and Jon Richardson are among the other comedians who are being linked to the project.
Walliams is currently working as a judge on the upcoming new series of Britain's Got Talent but recently admitted that he was nervous about pressing the buzzer.
Reports have also suggested that some of Walliams's comments have been too rude for the talent show.