Iain Duncan Smith has called for a re-writing of the Conservative leadership contest rules to avoid “chaos”.
Eleven MPs have declared so far that they will run to replace Theresa May, with the number expected to rise.
Mr Duncan Smith, who led the Tories from 2001 to 2003, told the BBC the number of MPs needed to nominate a candidate had to be increased.
And the party must look at eliminating more runners during early voting in order to speed up the contest, he said.
At the moment, only two MPs need to nominate a candidate for them to stand. Mr Duncan Smith said that threshold should rise to “10, maybe 12”.
“We need to present a face of a party that actually can get jobs done,” he said. “We don’t want to have this meandering around looking like chaos.”
He added: “I have never seen so many people lining up and there may be more.”
The contest gets fully under way on 7 June, when Mrs May stands down as Conservative leader.
MPs will hold a series of votes, during which the field will be whittled down one by one each time. When two candidates are left, they will go to a full vote of the Conservative Party membership.
Mr Duncan Smith suggested that, instead, two or three candidates should be removed in each round of the ballots held by Tory MPs, in order to “accelerate the process”.
BBC assistant political editor Norman Smith said he understood the executive of the 1922 committee of backbench Conservative MPs – which sets the contest rules – will meet next Monday to discuss the issue.
The leadership contest result is expected in late July, with the winner also becoming prime minister.
Mr Duncan Smith said only those with significant political experience should put their names forward.
“We have to be very focused that the person who wins this will, the day after, be the prime minister and have to pick up the pieces of Brexit and all the other elements,” he said.
“And that’s got to require someone who really knows where they are going.”
When asked at a press conference in London whether too many people were running to replace her, Mrs May said the UK was a “land of opportunity”.
Meanwhile, Chancellor Philip Hammond has said he would not “feel the need” to join the list of candidates if his views were “properly represented”.
Elsewhere, International Development Secretary Rory Stewart, who is running for the Tory leadership, has apologised for smoking opium – a class A drug in the UK – in Iran.
His admission came only days after Foreign Secretary Jeremy Hunt – another leadership candidate – told the Times that he once drank a cannabis lassi while backpacking through India.
The declared candidates are:
- Brexit minister James Cleverly
- Environment Secretary Michael Gove
- Health Secretary Matt Hancock
- Foreign Secretary Jeremy Hunt
- Home Secretary Sajid Javid
- Former Foreign Secretary Boris Johnson
- Former Leader of the House of Commons Andrea Leadsom
- Housing minister Kit Malthouse
- Former Work and Pensions Secretary Esther McVey
- Former Brexit Secretary Dominic Raab
- International Development Secretary Rory Stewart