Tim Farron shocked Westminster yesterday by quitting as Liberal Democrat leader despite his party gaining seats at last week's general election.
In itself, the decision to go was predictable: despite winning three extra seats, the Lib Dems saw their vote share shrink from 2015.
But Farron's reasoning was the surprise: the devoutly religious politician said scrutiny of his faith, and in particular his views on homosexuality, left him feeling "torn between living as a faithful Christian and serving as a political leader".
But with Farron gone, who are the candidates to replace the MP for Lonsdale and Westmorland?
Jo Swinson (Betfair 4/9, Ladbrokes 6/4)
A returning MP who lost her seat in 2015, Swinson served as a minister in the coalition government, covering both the business and women and equalities patches.
She won back the swing-seat of Dunbartonshire East last week having been deposed by the SNP in 2015, building a majority of 5,339 along the way.
Swinson is the early bookies' favourite and, at just 37 years old, could help represent a younger face for her party. However, she lacks the top-level experience of some of her peers.
Vince Cable (Betfair 4/1, Ladbrokes 3/1)
Former business secretary Cable is the second favourite with bookmakers, and enjoyed a high-profile election campaign after being named Farron's Treasury spokesman.
Another returning MP, this time in Twickenham, Cable briefly served as an interim leader while the party selected Nick Clegg.
Cable brings seniority to the table, but can be regarded as a loose cannon, having contradicted Farron on issues like a second Brexit referendum. And at 74, his age may be a factor.
Norman Lamb (Betfair 4/1, Ladbrokes 2/1)
Lamb has built cross-party respect for his work on mental health, both during the coalition and afterwards. While working with the Conservatives, Lamb was also one of the driving forces behind plans for a cap on the cost of social care, later abandoned by David Cameron.
A former solicitor, Lamb has been an MP since 2001, but lost out in the last leadership contest, which saw more than 30,000 votes cast.
Having been a senior figure under Farron, Lamb would need to present a clearly distinct agenda from his predecessor.
Ed Davey (Betfair 11/1, Ladbrokes 8/1)
Another former minister returning to parliament, Davey also recovered his south west London seat last week after being booted out in 2015.
Davey also has a track record as an outspoken campaigner on climate change issues and served as energy secretary in the coalition.
But could he be held back by his association with the decision to hand EDF the contract to build the Hinkley Point nuclear reactors?