Former Conservative leader Lord Hague has said that it “would be better” if the party’s leadership was decided by MPs, rather than the membership.

Tory members are preparing to select a new leader after Rishi Sunak announced he was standing down following the party’s general election defeat in the summer.

Kemi Badenoch, Robert Jenrick, James Cleverly and Tom Tugendhat are all vying for the party leadership, and will get a chance to address the party’s membership at the conference in Birmingham which gets under way on Sunday.

Speaking to the BBC’s Westminster Hour, Lord Hague – who led the party after its defeat in 1997 – said that membership had “become so small”.

Asked about the membership making the final decision on who will be party leader, Lord Hague told the Radio 4 programme: “That’s my fault, I introduced these rules.

“But now we can see the world has changed, political parties are smaller.

“It would be better if the decision was in the hands of Members of Parliament because the party membership has become so small.”

However, he said that MPs “still play a very big role” so “they have to be very careful who they support in case they give the impression to the members that they’re happy with someone they’re not really happy with”.

The race for the Tory leadership will feature prominently in the party’s conference.

The four candidates will be lobbying MPs before parliamentarians pick the final two on October 10. Members will choose between those two, with the result declared on November 2.

Lord Hague warned the winner that there will be “a long haul”.

Asked in the same Westminster Hour interview what advice he would give the winner, he said: “The Labour government will be vulnerable, even in four or five years’ time.

“But that does not mean that people will see the Conservatives as the natural replacement for them, unless we have a very single-minded leader who can communicate values, appeal to new generations and talk about the issues of the future.”