Conservative Party chairman Mr Michael Ancram is set to become the fourth candidate for leadership of the party later today.
Sources close to his campaign say he will stand on a platform of traditional Tory values.
It is thought Mr Ancram was encouraged to stand by positive soundings from senior figures in the constituencies. He has also won some support among colleagues at Westminster.
Ms Ann Widdecombe - who was initially considering fighting for the party's top job herself - said: "I can't comment on whether Mr Ancram is going to stand but certainly, if he declares, I will support him."
Mr Ancram's announcement will come just hours after Mr Michael Portillo officially launches his campaign with a call for a wholesale revival of the party to attract young activists.
Mr Portillo is believed to have already established a sizeable lead over fellow contenders Mr David Davis and Mr Iain Duncan Smith among fellow members of the shadow cabinet and Tory MPs.
But the final choice of leader will be in the hands of the 350,000 grassroots Tory activists, who will choose from a shortlist of two emerging from the MPs' ballot.
PA
