Tory leadership hopeful Rory Stewart has said he has the necessary eight signatures to get through to the first round of voting.
Candidates have until 5pm today to express their desire to be involved in the first round of the contest, with MPs then voting on their favourite for the job.
Once the nominations close, Conservative MPs will vote for their preferred candidate in a series of ballots held on June 13, 18, 19 and 20.
Contenders will then be whittled down one by one until there are only two remaining.
Speaking earlier on Radio 4, Rory Stewart confirmed he had the eight nominations needed to compete in the leadership contest.
Mr Stewart will hold a rally tomorrow on the Southbank in London at 5.30pm.
The MP for Penrith and the Border used Twitter to call on fellow leadership hopeful Boris Johnson to rule out proroguing parliament
He tweeted: "As for Boris I am waiting to see if he is prepared to confirm - clearly and exactly - that he won’t prorogue parliament!!"
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