The search for a new Director General of the Royal Society for the Prevention of Cruelty to Animals has dissolved into acrimony. Two members of the panel appointed to choose a successor to Peter Davies say they will resign if former Liberal Democrat MP Jackie Ballard, is given the job.

She was the favourite in a short list of four who will make presentations at the society's headquarters in Horsham, West Sussex, on Monday of this week before a decision is to be made.

But sources at the charity, which faces a financial crisis and is reviewing proposed cuts to its services to save money, say there was concern over Mrs Ballard's lack of financial experience.

The panel members who threatened to resign are understood to prefer Steve Marshall, the former chief executive of Railtrack.

There are fears that his involvement with the rail company could hold up the charity to ridicule. But his supporters point to his success before he joined Railtrack, which included time as chief executive of Thorn plc.

His interest in animal welfare has been widely reported and he recently joined the board of the Chimpanzee Rehabilitation Trust.

An RSPCA source said: "Ballard is vehemently anti-hunting, but there's much more to running the RSPCA than that.

"Her past is as a social worker, a college lecturer and an MP. She hasn't run a large organisation and has no experience with finance, and that's where the RSPCA faces real problems at the moment.

"Members of the panel were also concerned that, despite living in Iran after losing her seat at the election last year, she didn't seem very well informed about the animal welfare issues surrounding halal meat."

Mrs Ballard was supported by Dr Richard Ryder, the charity's chairman and one of the panel of six members of its ruling council interviewing her earlier this week. She is also understood to have the support of David Thomas, who chaired the panel. He will have the casting vote if it cannot agree.

Two members, understood to be Jackie Denham and Linda Rimington, have written to the rest of the panel to say that they will resign from the charity if Mrs Ballard's name goes forward to the full council for approval.

The other two short-listed candidates are Michelle Thew, chief executive of the British Union for the Abolition of Vivisection, and Major General Michael Laurie.

A fifth short-listed candidate, Alec McGiven, who was director of England's failed bid to host the 2006 World Cup, withdrew before the interviews were held.

A member of the ruling council said: "The choice is between a failed MP who was a social worker and someone who ran a company which lost hundreds of millions of pounds. It's not good."