At a packed public meeting at St Clare's College in Griffith attended by opposition leader Bill Shorten, Liberal senator Zed Seselja listed the benefits of the federal government's new policy, spruiking an overall funding boost of $18.6 billion.

However, the former St Thomas the Apostle Primary student said socioeconomic scores - the basis of the new funding model - often failed to reflect the true extent of need in the ACT.

"Whilst the SES model we can have academic debates about how it works across the country, if I look at how it applies across the ACT, if applied in a fairly pure way, I think it can have some pretty significantly negative consequences," Senator Seselja said.

"My strong urging to [Education Minister Simon Birmingham] has been to have a look at the ACT and how it applies. My commitment to you tonight is to continue to push for that with the minister, to get the best possible deal for the ACT."

Senator Seselja later indicated funding was not frozen for Catholic systemic students with additional needs as feared by affected schools. He also described Senator Birmingham as "receptive" to his arguments.

Liberal MLA Andrew Wall, also Catholic educated and enrolling his daughter in a Catholic systemic school, said his experience showed parents chose Catholic education for its values rather than status.

"The Canberra Liberals are right behind you as parents, teachers and supporters of Catholic education, and we will fight with you for a model that values not only the great work that Catholic schools do locally but is also fair for the thousands of families that make the choice for Catholic education in the ACT," he said to applause.

Dubbed Gonski 2.0, the federal government's new schools funding policy will scrap 27 different deals made by the former government and transition all schools to needs-based funding within a decade rather than taking up to 150 years.

In the ACT, this will mean an increase in funding for public schools, while Catholic systemic schools say they face a funding freeze. Funding for Catholic schools in the ACT is expected to increase by $2 million over the forward estimates.

Nine of the ACT's independent schools are funded above the school resourcing standard and may face cuts or slower-than-expected growth. Radford College and Daramalan College, each of which received more than 190 per cent of the school resourcing standard this year, have acknowledged the new policy will likely lead to less funding.

Canberra Grammar, which received 140.1 per cent of the school resourcing standard, will not have any funding cut. Emmaus Christian School this year received 128.7 per cent of the school resourcing standard but will face a reduction.

Emmaus principal Erik Hofsink said last week's announcement came as a surprise but "we'll await the detail, support good policy and talk with the powers that be about working through the adjustment".

Australian Association of Christian Schools executive officer Martin Hanscamp, representing more than 100 Christian schools including Emmaus, wrote to Senator Birmingham "to stand and applaud what we see [as] good policy action".

"Whilst we'll take up the minister on his offer of discussing adjustment arrangements for our two schools [facing cuts], we're not seeking 'special deals' or mechanisms that will make the model a farce," he wrote.

"Rather than join the line of critics, from those affected, who have responded from their self-interest perspective, we'd like to loudly applaud a policy approach that is good for all schools and sectors and, as has been said, provides an the opportunity to put an end to the ridiculous school funding wars."

The policy has also been welcomed by the ACT Council of Parents and Citizens Association, representing public schools, but protested by the Australian Education Union. The union and opposition have argued the government's plan represents a substantial cut as it is $22 billion less than what was offered under the former Labor government's policy.

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