Western Sydney MP Ed Husic sought to move debate on Israel and Palestine at Labor's national conference to reinforce criticism of Israel's actions in Palestine and acknowledge a "genocide" in the Gaza Strip.
However, the motion wasn't seconded, effectively blocking the debate from proceeding following a push from factional leaders.
Mr Husic said he would continue to press the issue within the party.
"It's a big disappointment because we haven't had a chance to talk to an issue that means a lot not just to people inside that convention centre, but to party members who are outside," he told reporters in Adelaide.
"I've seen some of the big debates and big issues of the time being discussed on the floor of the conference.
"I have been surprised at the extraordinary amount of energy that has been applied to stop this, as opposed to talking about this."
Mr Husic said he was committed to remaining in the party despite the setback.
"Sometimes you'll be at the front and on your own, and suddenly find you've got a lot of people around you," he said.
"It might take some time to get there.
"Change sometimes involves difficult conversations to bring people together."
Instead, Labor MPs Josh Burns, who is Jewish, and Basem Abdo, who is from a Palestinian background, will address the conference and endorse the party's platform.
The draft policy platform, which prompted criticism from Israel's embassy to Australia, called for Israel to comply with obligations as an occupying power.
"Labor opposes the annexation of Palestinian territory and wants Israel to bring its illegal settlement activity and the occupation to an end, to see security for Palestine, for Israel and for the region," the policy said.
"Labor urges the government to prevent any support being given to illegal settlement activity or extremist settler violence, and to implement further action and sanctions as necessary."
Mr Husic said not being able to debate the draft position placed in the policy platform was unhealthy for the party.
"The national policy forum ... had made these positions and then ever became like a sacrosanct document that could not, in its pristine nature, be changed or altered at all, and no other views could be taken into account," he said.
Debate on the AUKUS submarine program, which has prompted criticism from rank-and-file members, also failed to make the conference floor.
The threat of Pauline Hanson has dominated proceedings at Labor's triennial conference, with One Nation outperforming the government on a primary vote in several opinion polls.
Former federal treasurer and party president Wayne Swan said One Nation and its leader Senator Hanson represented the latest challenge for the party.
"Let's not kid ourselves, the stakes are high," he said at a dinner on Friday night where he was awarded a Labor life membership.
"As our friends across the globe have found, authoritarians can emerge in a flash.
"There are polls now suggesting the tide may be turning on Hanson ... the tide has not turned. We are engaged in the battle."
Mr Swan said the conservative mantle once taken up in his home state of Queensland by former premier Joh Bjelke-Petersen was now in the hands of Senator Hanson.
"In Queensland, we know the shape of this fight," he said.
"It runs through the late '80s with Joh, the original Pauline Hanson. We stopped his caravan rolling to Canberra when it looked like it had unstoppable momentum.
"It finds its expression today in the fight against Hanson herself."