The Liberal Party is bitterly divided over changes to section 18c of the Racial Discrimination Act, which makes it illegal to offend, insult, humiliate or intimidate a person on the basis of their race, colour, national or ethnic origin. A fierce and long-running debate is expected to come to a head at party room meeting in Canberra on Tuesday.

In an extraordinary case of timing, the Coalition will debate removing protections in Australia's race hate laws on what is also the International Day for the Elimination of Racial Discrimination.

Prime Minister Malcolm Turnbull's ministry and then cabinet met on Monday night to discuss removing "offend" and "insult" from the act and replacing it with the word "harass", as well as other measures.

Support for this change is gathering momentum in the upper echelons of the Turnbull government, but a proposal to also drop "humiliate" has lost support.

But Nick Xenophon, who commands a bloc of three votes in the Senate, told Fairfax Media: "We are not convinced on these substantive changes to the wording. We want to see how the proposed process changes go first."

His colleague, senator Stirling Griff said he did not "personally" support removing offend and insult from the act, but added the party's position would be finalised when a proposal was released by the Turnbull government. A spokeswoman for senator Skye Kakoschke-Moore confirmed she also opposed removing offend and insult.

These statements leave the government with little room to move and indicate a push to change the wording of 18c is likely to fail. The Nick Xenophon Team's three votes, combined with Labor's 26 and the Greens' nine, form a bloc of 38 votes opposed to change, a majority in the 76-seat Senate.

However changes to the operation of the Human Rights Commission are more likely to find political support. The commission would be streamlined to allow vexatious complaints to be knocked out at an earlier stage, time limits would be placed on disputes and a new recourse introduced to appeal to the commission's president.

These procedural changes are likely to win broad support in the Liberal party room.

A separate proposal from Liberal frontbencher Concetta Fierravanti-Wells to insert a "reasonable Australian" test in the act is also on the table and could be debated on Monday night.

MPs who support dropping words from 18c, including the Institute of Public Affairs-aligned Tim Wilson and senator James Paterson, argue the change will strengthen freedom of speech in Australia.

But Liberal moderates led by Craig Laundy, David Coleman and Russell Broadbent are fighting a rearguard action to stop big changes, fearing it will alienate ethnic communities – as it did under Tony Abbott in 2014 – and cost them votes and seats.

Mr Turnbull declined to offer a personal view on whether to remove offend or insult on Monday.

"The government has a view on matters of this kind, the government will have a response. It will be the collective response of the government."

Liberal MPs calling for changes to the act believe Mr Turnbull must push for wording changes to please the disgruntled party base.

Executive Council of Australian Jewry director Peter Wertheim said removing offend, insult or intimidate was "bad policy and bad politics".

"It would have to substantially change the sections' construction by the courts, resulting in more litigation, not less," he said.

Opposition leader Bill Shorten said Tuesday's party room meeting was a test of Mr Turnbull's leadership.

"Will he back the 'right to be a bigot', or will he back modern, multicultural Australia?"

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