The race to become the next prime minister is set to narrow as Conservative MPs hold the first ballot of the contest following a week of leadership pitches.
Frontrunner Boris Johnson and Home Secretary Sajid Javid were the final two of the 10 candidates to launch their campaigns, as the battle for Number 10 intensifies.
Leadership hopefuls need at least 17 votes in the secret ballot to go through to the second round, with anyone below the threshold automatically eliminated.
But even if all the candidates meet the target, the one with the lowest number of votes overall will still have to exit the race.
Mr Johnson launched his bid with a warning to MPs that they will “reap the whirlwind” if they try to thwart Brexit - and said it was essential that Britain was out of the EU by the end of October.
But Mr Javid dismissed the former foreign secretary as “yesterday’s news”, saying the party needed to show it had changed.
Former Commons leader Andrea Leadsom insisted she was “very optimistic” about the ballot, and said she thought that she had the support to get through Thursday’s vote - despite a relatively low number of public endorsements.
She told ITV’s Peston: “There’s a whole range of colleagues who for one reason or another don’t want to declare for one candidate or another and I’m very optimistic about tomorrow.
“But tomorrow’s a big day, and we’ll see some real facts tomorrow - before then it’s all just speculation.”
Former chief whip Mark Harper, ex-work and pensions secretary Esther McVey and International Development Secretary Rory Stewart may also struggle to get over the line on Thursday.
But Mr Harper said: “I’m confident about getting through tomorrow based on the feedback that I’ve had from my colleagues, from my campaign launch yesterday and the various hustings that we’ve had.”
Meanwhile, Labour said it would continue to fight to prevent a no-deal Brexit after the latest cross-party attempt by MPs to take control of Commons business was narrowly voted down.
The cross-party motion, which would have enabled MPs to take control of the business of the House on June 25, was defeated by 309 to 298 - a majority of 11.
Ten Tories - including Ken Clarke, Sir Oliver Letwin, Justine Greening and Dominic Grieve - supported the motion, but eight Labour MPs voted against.
Shadow Brexit secretary Sir Keir Starmer said it would have acted as a “safety valve” enabling Parliament to pass legislation preventing the next prime minister from taking Britain out of the EU without a deal.
Thursday’s ballot is due to take place between 10am and 12pm, with the result due to be announced at 1pm.