Liberal Senator Gary Humphries.

Liberal Senator Gary Humphries. Photo: Andrew Meares

Canberra Liberals executives look certain to face a challenge under the party's constitution over handling of this month's Senate preselection.

And incumbent senator Gary Humphries has written to party members expressing his unhappiness at the process used to choose the party's No.1 upper house candidate for the federal election.

A group of dissatisfied members, led by former ACT divisional president Gary Kent, now have the 30 signatures they need to force a divisional council meeting, effectively an extraordinary general meeting, to try and have the preselection process overturned.

Tio Faulkner, president of the Canberra Liberals party.

Tio Faulkner, president of the Canberra Liberals party. Photo: Melissa Adams

Both Senator Humphries and Mr Kent's group say that members were not given time to qualify as voters in the preselection before outgoing party leader Zed Seselja announced his candidacy.

But current president Tio Faulkner publicly rejected the claims last week, telling members and the media that the whole process had been undertaken in accordance with party rules. In an email to division members, Senator Humphries challenged last week's public statement by Mr Faulkner that claimed the senator had ''raised no objection at the time, or in the interim'' to the process.

''This is untrue,'' Mr Humphries said in his email.

Mr Humphries, who did not sit on the management committee for any decisions relating to the preselection, said he repeatedly raised concerns with the committee about the process and they were ignored.

''I had repeatedly asked the management committee, through a third party, to conduct the preselection during 2012,'' the Senator wrote.

''I argued that it was dangerous to conduct a preselection in what would be an election year, noting that every other state division of the Liberal Party had concluded its Senate preselection before the end of 2012.

''These concerns were repeatedly ignored by the management committee.''

Senator Humphries said he had not argued that the division's process had breached the party's constitution, but he did argue that Mr Seselja's late nomination had ''seriously distorted the process of choosing a candidate''.

The senator said that in previous contested preselections there had been ample notice that there were rival candidates so that members could refresh their eligibility to vote but that ''has not been the case here''.

''I remain deeply concerned that a decision of this significance - the choosing of who should represent the ACT in the Senate - is being made on such a small franchise,'' he said.

''In my view every paid-up member of the party in the ACT deserves to have their say, if they want it.

''The management committee's decision on Wednesday night will, unfortunately, ensure that this does not occur.''

Mr Kent, a long-time internal critic of Mr Seselja, wrote to potential supporters suggesting they collect signatures to force the divisional council to overturn the decisions of the management committee.

He says he now has enough support to force the meeting but it is unlikely to be held until March, after the scheduled date of the preselection, February 23.