There had been reports the Brisbane prop was considering switching back to Australia for the 2026 tournament, but the 26-year-old has quashed those suggestions.Haas, who has Samoan heritage through his mother Joan Haas, committed to Toa Samoa for last year's Pacific Championships after previously playing four Tests with Australia.
He helped lift Samoa into the Pacific Cup final after starring in a 34-6 win over Tonga.
The powerhouse front-rower is a man of his word and said there was no way he had considered making himself available for the Kangaroos.
"I made my decision last year to move to Samoa from Australia," Haas said.
"The kind of person I am, I wouldn't back flip on them. I want to represent my mum, my grandmother and my granddad as well and there is no way in hell that I would (back flip)."
Haas is already on his way to being recognised as an all-time great, but lifting Samoa to World Cup glory would be a huge achievement and has the potential to raise Pacific rugby league to another level.
Samoa have been drawn in the same pool as France, Papua New Guinea and Tonga for the 10-team tournament to be hosted by Australia, New Zealand and PNG in October and November this year.
Haas is a key member of a Samoa forward pack that boasts the likes of Francis Molo, Jaydn Su'A, Simi Sasagi, Junior Paulo and Terrell May.
The backline includes premiership-winning stars Jarome Luai, Brian To'o and Stephen Crichton. Dolphins flyer Hamiso Tabuai-Fidow has also committed for the World Cup.
There is a sense the side can go one better than their 2022 World Cup performance, when beaten by Australia in the final.
"With the kind of calibre of players we have got there is a great chance, but that is still far away," Haas said.
"This is my last two months here so I am trying to focus on the Broncs."
Last week Haas dominated the State of Origin decider for NSW, terrorising Queensland up front in a stunning 30-12 win. It was his third Origin series win when playing all three matches and his second in a decider at Suncorp Stadium.
Last year's premiership win with Brisbane ticked that box and Haas also was named the club's player of the year for a sixth time.
He is without doubt the Broncos' greatest player of the decade and a worthy successor to the likes of Glenn Lazarus, Shane Webcke, Petero Civoniceva and Brad Thorn.
Haas will join South Sydney next year, but is fully committed to reviving Brisbane's spluttering season as they target winning all eight of their remaining matches to give themselves a chance of defending their title.
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