Michael Ancram has warned that denying party members a say in selecting the next Conservative leader will not make the party more appealing to voters.
Mr Ancram has run for Tory leader in the past
The Conservative deputy leader was speaking ahead of a speech in which he set out his vision for the party.
He said that since they got rid of Margaret Thatcher, Conservatives have lacked both a vision and a mission.
"What I'm trying to do is to set out very simply the principles of the Conservative party," he said.
He warned that reducing the franchise for choosing the party leader will not enhance the party's "political relevance".
"Rather than restricting or removing the franchise, we should be looking to extend it in a way which will attract the enlistment of a much wider representation. To do that we must show our membership that we value them."
Tory leader Michael Howard announced the day after the election that he would step down by Christmas, once a new system for choosing his successor had been agreed.
Until 1997 the choice of leader was entirely in the hands of Conservative MPs.
That was changed under William Hague's leadership to a system where party members chose from a shortlist of two chosen drawn up by Conservative MPs.
Mr Howard backed new leadership election rules which would have given the rank and file an influence in the process but left Tory MPs with the final vote.
However that option was rejected by Conservative MPs who are backing an option that gives them the entire say, albeit after an indicative vote among constituency party chairmen.
Mr Ancram, who previously ran for leader after the resignation of William Hague in 2001, argued in his speech that the party needs to find a consensus of what a "Conservative is today".
"The Conservative Party historically has always had to bring itself up to date, but always consistent with its principles," he said.
"These views, however, only become relevant once the basic principles are agreed. It is agreeing principles that must now be the priority. If we fail to take this opportunity, then our party will remain in the political wilderness."
He stressed that key to their rehabilitation is demonstrating Tories listen and respond to real people, not to "political elites and questionable focus groups".
"Freedom of the individual lies at the heart of Conservatism and sets us apart from those who believe the state knows best," he argued.
"It must be the driving engine of Conservatism today, only to be restrained when it unfairly exploits or curtails the freedom of others."
Mr Ancram called for lower taxes, a "bonfire of red tape" and the encouragement of enterprise.