The United Progressive Kinabalu Organisation (Upko) has become the fourth member of the Pakatan Harapan (PH) coalition.
The Sabah-based party has one MP in the Dewan Rakyat, president Wilfred Madius Tangau.
In a statement today, PH secretary-general Saifuddin Nasution Ismail said PKR, Amanah and DAP agreed to accept the former Barisan Nasional party into its fold.
“We believe that this will strengthen PH in its effort to face the general election,” he said.
Meanwhile, Saifuddin said PH will also further strengthen its ties and co-operation with other opposition parties – such as Pejuang, Warisan and Muda – and independent lawmakers.
He thanked the parties for nominating PKR president Anwar Ibrahim as their candidate for prime minister last week.
“PH will ensure that the opposition bloc is more effective and ready for the 15th general election.
“Our doors are always open to work with other opposition parties, and we even welcome them to be part of PH,” he said.
Last week, Anwar said the outcome of the political crisis that saw Ismail Sabri Yaakob appointed prime minister showed the opposition must work harder for the upcoming election.
Yesterday, Sarawak opposition party Parti Sarawak Bersatu (PSB) announced that they will not join PH and will continue to remain independent without affiliation to any political alliance.
Its president Datuk Seri Wong Soon Koh, however, said PSB had recently supported Anwar as prime minister candidate to respect the wishes of voters in the 14th General Election.
PSB had two MPs among 105 who backed Anwar last week.