Senator Fatima Payman faces possible expulsion after defying her party to become the first Labor senator to cross the floor in almost two decades.

Payman maintains she voted in line with her convictions by supporting Palestinian statehood as her colleagues voted against it.

She backed a Greens motion that sought to have the upper house declare recognising Palestinian statehood an urgent matter.

Her vote on Tuesday’s Senate motion could cost the Western Australian her spot in the Labor caucus, with her fate in the hands of her caucus colleagues.

Labor members are expected to follow the party’s position but there is no mandated sanction for crossing the floor. It’s the first time a party member has crossed the floor since 2005.

“I said I will follow my conscience,” Payman said in comments carried by SBS News when asked about her decision to cross the floor.

“What our rank and file members have been asking us is for us to do more as a party … that takes pride in our fight towards human rights and being champions of justice.”

A decision to expel Payman is one for caucus while her Labor membership will be left in the hands of the national executive.

But senior Liberal senator Simon Birmingham said Payman’s actions constituted a direct challenge to Prime Minister Anthony Albanese’s leadership.

The Executive Council of Australian Jewry also condemned the vote to support Palestinian statehood.

But the Australian Federation of Islamic Councils welcomed Payman’s support.

The recognition of Palestinian statehood would set a significant step forward with it being a matter of human rights, dignity and justice that should traverse political lines, council president Rateb Jneid said.

The Greens also supported Payman, with Mehreen Farqui – who moved the motion – saying the Labor member had stood by her convictions and showed “real moral courage”.

Payman did not resign after crossing the floor, saying she believed it was within Labor’s policy platform and she upheld the party’s values.

It’s Labor policy to recognise a Palestinian state, but with no timeline and some caveats attached.

“I was not elected as a token representative of diversity, I was elected to serve the people of Western Australia and uphold the values instilled in me by my late father,” Payman said.

“We cannot believe in a two-state solution and only recognise one.”

Foreign Minister Penny Wong has slightly shifted Labor’s position, saying recognition can no longer wait until the end of a negotiated peace process.

Birmingham, who is the opposition’s foreign affairs spokesman, said recognition could come only after Palestinian officials and the Palestinian Authority agreed Israel had the right to exist as a democratic and Jewish state.

Hamas could play no role in the state – which meant all remaining hostages needed to be released – and appropriate security guarantees between parties within recognised borders had to be put in place, he said.

Payman has also joined with the Greens and crossbenchers to call on the government to take a stronger stance against Israel’s actions in Gaza, with the death toll surpassing 37,000, according to the Hamas-run local health ministry.

A United Nations inquiry found both Israel and Hamas have committed war crimes after the designated terrorist organisation killed 1200 Israelis and took 250 hostages in an attack on October 7.

The scale of killing in Gaza, use of starvation and failure to supply essentials such as food, water, shelter and medicine were found to be war crimes conducted by Israel.

The federal government has called on Israel to abide by international humanitarian law and said it was “gravely concerned” at the inquiry’s finding.

Palestinian supporters want outright condemnation and accountability.

-with AAP