First round results are expected at around 7pm, when the candidate with the lowest number of votes will be eliminated
Conservative MPs in the UK have begun voting for their new party leader and the country's next prime minister, with Theresa May the frontrunner to replace David Cameron.
Some 330 MPs are voting in a ballot which will be overseen by the backbench 1922 Committee and its chairman Graham Brady, with the result set to be announced shortly after 6pm.
The candidate with the fewest votes will be eliminated, with another ballot taking place on Thursday.
The process is repeated until there are just two candidates remaining, when 150,000 party members across the country will make their choice by postal ballot.
Mrs May's closest rival is energy minister Andrea Leadsom, who has the support of 40 MPs compared to May's 122, according to Sky News figures.
Paddy Power says the odds of Mrs Leadsom winning have gone from 16/1 to 9/4. However, Mrs May remains a clear frontrunner, with odds of 2/5.
Justice Secretary Michael Gove - who was initially the favourite - is struggling to match Mrs Leadsom's support, with 27 backers, while Work and Pensions Secretary Stephen Crabb, who is pitching himself as the anti-establishment candidate, has 25 MPs in his corner.
Liam Fox is likely to be the first candidate to be eliminated, with just eight MPs publicly backing the former Defence Secretary.
When asked about his prospects, Dr Fox said: "To be frank, given that half the electorate are currently uncommitted and half the electorate come from the 2015 intake and have never been through one of these campaigns before, none of us really know what the outcome is going to be.
"The only thing you can say is we're likely to get some surprises in the result."
Mr Gove, Mrs Leadsom and Dr Fox all backed Brexit, while Mrs May and Mr Crabb were on the Remain side.
The vote comes after a Cabinet meeting this morning to discuss Britain's vote to leave the EU, a result that prompted Mr Cameron to announce he would stand down.
Mrs Leadsom received a boost in her bid to replace the prime minister on Monday when Vote Leave figurehead Boris Johnson threw his weight behind her.
Speaking as he left his home to cast his vote, Mr Johnson said: "It's time for a candidate that will embody change and dynamism and a forward-looking approach. We've had a lot of gloom.
"Andrea has massive experience of finance, she understands the European issue backwards and she has a very positive vision for what this country can achieve outside the European Union."
The former London mayor's support for Mrs Leadsom's campaign is widely seen as an act of revenge against Mr Gove, who was expected to back Mr Johnson's own bid for the Conservative leadership.