The contest to replace Vince Cable as Liberal Democrat deputy leader got under way today as MP Tim Farron became the first to declare his candidacy.
Mr Cable announced last night that he would step down from the position in order to concentrate on his role as Business Secretary in the Government.
A successor will be chosen on June 9 and Mr Farron said he wanted to take the role to help maintain the "independence" of the party within the coalition with the Tories.
The MP for Westmorland and Lonsdale was among rebels who quit Nick Clegg's front bench over EU policy in 2008 - but was later restored to the top team by the party leader.
Among his backers is former party leader Sir Menzies Campbell, whom he served as Commons aide before playing the same role for Mr Cable while he was interim leader.
Mr Farron said: "We were right to enter this coalition because it was in the national interest to do so and because at long last it has given us the chance to create a fair, free and green country.
"But it is also vital that the independence, radicalism and distinctiveness of the Liberal Democrats are maintained.
"I want to work alongside Nick Clegg to ensure that not only does the country benefit from this coalition, but that the Liberal Democrats' electoral prospects benefit too.
"We have Scottish Parliament, Welsh Assembly, local elections and a possible fair votes referendum all within the next year that the Liberal Democrats must win."
Sir Menzies said: "We need someone with substance in the role and someone who is both loyal and independent minded. Tim is one of the best communicators the party has, and represents a bright and confident future for the Liberal Democrats."
Any MPs with the required backing of five colleagues by the time the parliamentary party meets next Wednesday will go forward to a ballot the following week.