Gary Humphries in his Parliamentary office.

Gary Humphries in his Parliamentary office. Photo: Melissa Adams

Former ACT chief minister and ousted senator Gary Humphries says a malaise is afflicting the Canberra Liberals and the party faces years in the electoral wilderness if it continues as a ''foot soldier'' for the Abbott government.

One year and one day after losing a bitter and drawn out Senate pre-selection contest to Zed Seselja, Mr Humphries used a Canberra Times opinion piece on Friday to fire a broadside at a party he calls overrun by a ''creeping conservatism''.

He argues the party is guilty of a series of policy and messaging failures under Opposition Leader Jeremy Hanson.

Mr Humphries said conservative MLAs ignored popular electoral support for same-sex marriage reforms last year, remaining stubborn through personal opposition to marriage equality.

The party is failing to effectively fight public service job losses since the election of Tony Abbott, in contrast to former chief minister Kate Carnell, who opposed cuts by the Howard government in the 1990s.

Writing that Labor had become the natural party of government in the ACT, Mr Humphries said there was little chance of a Liberal territory government after the 2016 election unless ACT Labor stumbles.

Calling on the party to differentiate itself from the federal government, the former leader said the Liberal philosophy of small government created a distaste for the party brand in Canberra's large public service community.

''We need to do more than simply be the alternative when voters grow tired of ACT Labor, because there are presently few signs of Katy Gallagher going the way of Anna Bligh, Kristina Keneally or Julia Gillard.''

Serving in the Senate from 2003 until last year, Mr Humphries now works as a lobbyist.

Mr Hanson rejected the criticism on Thursday. ''I understand that Gary is bitter and frustrated after losing the support of the Liberal Party's membership in last year's Senate preselection contest but I am disappointed that he hasn't got more positive contributions to make,'' he said.

''I reject the suggestion that we should simply mimic Labor and the Greens for cheap political expediency.''

He said the Canberra Liberals had the most Legislative Assembly seats in the party's history and had secured a larger primary vote than Labor at the 2012 election.

''The MLAs are united and effective, and as a Liberal Party we are getting on with the job of holding the Labor government to account,'' Mr Hanson said. ''We will continue our hard work in the community and will continue to develop and present our alternative plans for Canberra.''