Canberra Liberals MLAs backed their former leader on Tuesday as the party's No.1 Senate candidate and in a letter to the party's membership called on preselectors to do the same in Saturday's vote.

The ACT division's former president Winnifred Rosser has also written to members urging them to vote for Mr Seselja over incumbent senator Gary Humphries.

But Senator Humphries, who is battling to retain his upper house seat, said the Liberals MLAs were only united in that they wanted Mr Seselja to ''leave the Assembly as soon as possible''.

Mr Seselja's Assembly colleagues wrote that their former leader ''had the runs on the board to be an effective advocate in the Senate for the Liberals and the ACT''.

''In 2012, as leader of the Canberra Liberals, Zed took us to a record eight seats whilst bringing the Greens down to just one representative,'' they said.

As internal feuding over the party's management of the preselection continued on Tuesday, new Opposition Leader Jeremy Hanson described the process as ''democracy in action''.

''I think these preselections are difficult,'' Mr Hanson said. ''You've got democracy in action here. You've got two candidates.

''But I'm very confident that once we have a result on Saturday that the whole party will unite behind that candidate and take on our real combatants, the Labor Party and the Greens.''

Ms Rosser wrote that while she respected the work Senator Humphries had done over many years in ACT politics, Mr Seselja had ''the drive, the energy, the capacity and the track record to deliver the best possible result for the Liberal Party in the ACT at a federal level''.

Mr Seselja welcomed the support of his Liberals Assembly colleagues. ''I think it's a very rare thing for a party room to have a unanimous view on something like this,'' he said. ''These things are contentious. There will always be differing views within political parties on these issues. But to have the entire parliamentary party, many of whom I have worked very closely with over the last few years, it's a great honour.''The former local leader hit out at the ongoing public commentary about the preselection, saying the publicity had been ''unhelpful''.

The party has attempted to stop details of the internal brawl from becoming public, with both Mr Seselja and Liberals MLA Vicki Dunne writing to party members and pleading with them not to talk to media about the feud.

''There are some people who are determined to play these things out in the paper, particularly the behind-the-scenes details,'' Mr Seselja said.

''I'm not going to be making comments that are in any way destructive to my opponents or the political party of which I'm proud to be a member.''

Senator Humphries said the MLAs' loyalty to their former leader was ''touching but they seem to be united on one question - that Zed should leave the Assembly as soon as possible''. The Senator said he also had the ''more important'' endorsement of federal Liberal Party Leader Tony Abbott, as well as Deputy Leader Julie Bishop and senior frontbenchers including Joe Hockey, Eric Abetz and Christopher Pyne.

''The question of what is best for the Federal Parliament, I think, is probably a matter better left for federal MPs to comment on rather than local MPs,'' he said. ''I think what's more important in all of this is the opinion of the leader of the federal parliamentary party.''