"The two who I suspect [the public] regard as the 'prime minister candidates' who could take on Tony Blair and ... look like potential prime ministers are Michael Portillo and myself," he said.
Michael Portillo remains the favourite to come first in the ballot with either Michael Ancram or David Davis likely to be the first candidate eliminated from the race.
However the key focus since the weekend has been on whether Ken Clarke or Iain Duncan Smith will make it through to the final shortlist of two from which party members choose the winner.
The tide appeared to be turning toward Mr Duncan Smith - on Monday a major bookmaker stopped taking bets on the leadership after a flood of money was placed on the shadow defence secretary.
Right-wing MPs have been accused of plotting to make sure the pro-European Mr Clarke - whom opinion polls suggest is the preferred choice of voters and Tory supporters - does not get to that run-off stage.
But Ashford MP Damien Green, one of Mr Portillo's leading supporters, dismissed as "absolutely untrue" reports of a tactical voting plan to see off the former chancellor before party members vote.
Big Brother 'more democratic'
Mr Clarke has warned that the public would be "astonished" if he failed to win a place on the shortlist.
"The two who I suspect [the public] regard as the 'prime minister candidates' who could take on Tony Blair and ... look like potential prime ministers are Michael Portillo and myself," he said.
John Strafford, chairman of the Campaign for Conservative Democracy, said there was a "huge amount of manoeuvring" going on.
He told the BBC: "It is sad that the Big Brother TV programme is more democratic than this leadership contest because at least in Big Brother every member of the public is entitled to vote."
'Dark horse' keeps counsel
Meanwhile David Davis, the self-appointed "dark horse" candidate, has refused to rule out the possibility that he would withdraw from the race if he came fourth in the first round.
"I am already into the field and would expect, as people drop out, I would accelerate towards the front," he insisted.
The odds on Mr Duncan Smith, MP For Chingford and Woodford Green, winning the overall contest have dropped form 10-1 to 7-2 in the past days.
Timetable stretches to September
On Tuesday, voting by the 166 Tory MPs opens for the first-round ballot.
The candidate with least support is eliminated from the contest.
Others could throw in the towel if they believe they are unable to attract enough support to progress further, preferring to give their backing to another candidate instead.
If all candidates proceed, however, the timetable would be as follows: