Voting has now finished in the contest to replace Charles Kennedy as Liberal Democrat leader.
Sir Menzies Campbell, Simon Hughes and Chris Huhne all insist they can win following a month of campaigning.
The party's 73,000 members' postal ballots had to be returned by noon, ahead of a count and the announcement of the winner on Thursday.
Bookmakers say Treasury spokesman Mr Huhne is the favourite, followed by Sir Menzies and then Mr Hughes.
Tax pledges
The three candidates appeared together on BBC Two's Daily Politics show on Tuesday, in an effort to sway the final undecided Lib Dem voters.
Mr Huhne said his plans to cut income tax for the lowest earners - which would cost £21bn - could partially be offset by increasing "green" taxes.
Sir Menzies, the party's foreign affairs spokesman and acting leader, called for a written constitution for the UK and stressed his "experience" and "judgement".
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And Mr Hughes, the Lib Dem president, reiterated his demand for a timetable for British troops to withdraw from Iraq.
The contest to find a permanent replacement for Charles Kennedy was called after he resigned as leader in January, having admitted a drink problem.
The announcement of a winner on Thursday will come a day before the party's spring conference begins in Harrogate on Friday.
The bookmaker Paddypower has Mr Huhne as 4-7 favourite, with Sir Menzies at 5-4 and Mr Hughes at 16-1.
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