Boris Johnson and Rishi Sunak have held talks as they edge closer to the deadline for nominations in the contest to replace Liz Truss as UK prime minister, BBC News reported.

Two separate sources told the BBC the meeting took place, but neither camp has disclosed what they discussed.

Sunak continues to forge ahead in the race, gathering the support of 128 MPs from all wings of his party, including former Johnson allies.

Johnson is in second place with 53 backers, according to the BBC's tally. 

However his campaign claims he has the support of 100 MPs—the number required to officially enter the race.

Sunak's supporters raised doubts over this and called for the former PM to show proof.

Penny Mordaunt is the only candidate to officially declare they are in the race, but she lags behind on support with 23 MPs.

The hopefuls have until 14:00 BST on Monday to get enough support to run, qualifying them for the next stage of the race.

If the party's MPs get behind just one candidate, we could have a new prime minister by Monday afternoon.

But if not, it will then go to an online ballot of the Conservative party membership, with the result to be announced on Friday.

Polling suggests Johnson, who has returned from a Caribbean holiday to consider his options, would be favorite to win a members' vote.

Throughout Saturday, MPs were publicly declaring support for their favored candidate.

Sunak picked up backing from all wings of his party, including the right, and from figures like Johnson's former Chief of Staff Steve Barclay, his former Brexit Minister Lord Frost, Kemi Badenoch, the International Trade Secretary, and Northern Ireland Minister Steve Baker.

Sunak, who has yet to officially declare he is standing, also has the support of former chancellor and health secretary Sajid Javid, Security Minister Tom Tugendhat, former deputy prime minister Dominic Raab.

Pointing to the parliamentary probe facing Johnson, Raab told the BBC: "We cannot go backwards. We cannot have another episode of the Groundhog Day, of the soap opera of Partygate."

The former PM has so far won the support of six Cabinet ministers: Ben Wallace, Jacob Rees-Mogg, Simon Clarke, Chris Heaton-Harris, Alok Sharma, and Anne-Marie Trevelyan.

Also among supporters of Boris Johnson is former home secretary Priti Patel, who said Johnson could bring together a united team and lead the UK to a stronger and more prosperous future.