Mr Hague has embarked on a busy round of regional constituency meetings to put pressure on Tory MPs to back him, and his supporters claim he is ahead with grassroots members.
It is likely the first ballot will take place on 10 June - possibly the same day as the Budget - with party chairmen being allowed to cast their votes by telephone using a code number. The 164 Tory MPs will make up the rest of the votes.
Mr Hague will underline his commitment to a radical change in the party's voting system at a London rally tonight for over 300 supporters. His campaign was boosted yesterday with the backing of former Treasury minister John Maples.
The intervention by the chairman of the Conservative Party has made it almost certain that an immediate change in the rules to elect the leader will be agreed by the officers of the 1922 Committee of Tory MPs, who are being elected today.
It marks a partial victory for Robin Hodgson, the chairman of the party's voluntary wing, the National Union, who led the campaign for a 20 per cent share of the vote to be given to the Parliamentary constituency chairmen, Euro-constituency chairmen and the 200-strong National Union executive committee.
Proposing a compromise, Dr Mawhiney said: "We need to be clear that such a change would set a precedent for the principle of wider direct involvement in leadership elections. It should not, however, set a precedent for the mechanism."
Michael Howard, the former Home Secretary, tried to get his campaign back on the rails after the attack by Ann Widdecombe, a former minister, by issuing a policy pamphlet called The Future of Europe calling for a "pick and choose" arrangement in the EU for law and order, the Common Agriculture Policy and the Common Fisheries Policy.
"Only by allowing countries to pick and choose the policies which they wish to administer jointly can the EU regain the confidence of its peoples," he said.
He promptly came under fire from the Tory chairman of the MEPs, Tom Spencer. Those advocating withdrawal from the CAP showed how little they had learned from the May Day defeat, he said.
"What was rightly punished on May Day was the arrogance of a political party which had begun to assume that it had a right to perpetual power. That arrogance led it to indulge in internal feuding and press-driven paranoia about Europe," he told Surrey chambers of commerce.
Chris Patten yesterday ruled himself out of the race. Mr Patten, the Governor of Hong Kong, may have swept the boards for the leadership, if he had had a seat in Parliament enabling him to run.Reuse content