Dame Suzi Leather, the commission's chair, and Andrew Hind, its chief executive, told a committee of MPs last week that there were "strong arguments in favour" of having one.
An ombudsman could improve public accountability, they said, but could not interfere with trustees' independence to make strategic decisions. Hind said: "There would be a big question about whether charities are prepared to pay for one."
Commenting later, the NCVO said the sector did not need an ombudsman. "Charities are regulated by the commission and, if they deliver services, by the National Care Standards Commission," said senior policy officer Belinda Pratten.
Ben Wittenberg, director of policy and research at the Directory of Social Change, said that an ombudsman had an appeal for the commission, which was facing the prospect of an increased workload and a reduced budget.