The federal Liberal leadership race just got bit less crowded.

Longshot contender Alex Burton, a Vancouver Crown prosecutor, has dropped out of the contest.

More may follow as the deadline approaches for paying the hefty $75,000 entry fee imposed by the party.

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The second $25,000 instalment is due at the end of this week, although candidates can wait until mid-January to pay the entire fee in one lump.

Because the party levies a tithe of 10 per cent on every dollar raised by contenders, each candidate actually has to raise $82,500 to be able to pay the fee.

Mr. Burton's campaign manager, Kevin Chalmers, says Mr. Burton could have paid the fee but the problem was raising enough money beyond that to run a competitive campaign.

Mr. Burton had been running a shoestring campaign as it was, travelling across the country in a mobile home.

In a written statement, Mr. Burton said: "I have said that it is important to run in this race the same way as I would lead my party. That is to say, my leadership campaign would be run with fiscal discipline and a willingness to make tough decisions even when those choices lead me to a conclusion which I find difficult."

Mr. Burton said he'll focus now on running as a Liberal candidate in the 2015 election.

Mr. Chalmers said there were other hurdles to Mr. Burton's leadership candidacy beyond money, including the fact that Mr. Burton does not have a seat in Parliament or insider access to party membership lists.

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So far, six candidates have officially registered with the party, which includes filing the required nomination papers and plunking down the first $25,000 instalment of the entry fee. They are Montreal MP Justin Trudeau, the prohibitive favourite; fellow Montreal MP Marc Garneau, Canada's first astronaut; Vancouver MP Joyce Murray; former MP Martha Hall Findlay; retired Canadian Forces Lt. Col. Karen McCrimmon; and Toronto-based lawyer Deborah Coyne.

Others who've launched their campaigns but have yet to register include Toronto lawyer and technology guru George Takach, Ottawa lawyer David Bertschi and David Merner, former president of the party's British Columbia wing. Ontario government economist Jonathan Mousley has declared his intention to run if he can raise sufficient funds.