Lajim said on Sunday that his party will join as a "component" of the currently three-party coalition, and not as part of a loose electoral pact.
This adds a fourth member to the coalition, which is currently made up of Parti Cinta Sabah, the State Reform Party and the Sabah Progressive Party.
With this, the only local Opposition party currently out of the alliance is Parti Warisan Sabah headed by former Umno vice president Datuk Seri Mohd Shafie Apdal.
"We have decided Parti Harapan Rakyat Sabah will join Gabungan Sabah to face the ruling Barisan Nasional at the coming general election in order to increase the chance to defeat the ruling coalition," Lajim said at a gathering in Kuala Penyu on Sunday.
The former PKR member also said he is confident that the four parties could work out the arrangement of seats among them.
"We can even work with Pakatan Harapan, provided they will pave the way for Sabah-based parties to lead the field in Sabah," he said, adding that local parties should best be let to dominate the state and not peninsula-based parties.
By Ruben Sario
