The opposition Parti Islam SeMalaysia (PAS) has been dealt a blow in the swing state of Kedah after the state assembly's opposition leader Amiruddin Hamzah left the Islamic party to join a party founded by former prime minister Mahathir Mohamad.
And more such defections are expected in the run-up to the general election, which is due by August next year.
The Anak Bukit assemblyman's decision to join Parti Pribumi Bersatu Malaysia (PPBM) weakens an already hamstrung PAS in the northern state.
It will also hurt Prime Minister Najib Razak's Umno party at the polls, where three-cornered contests are expected.
With the opposition support split, the balance now tilts towards the four-party Pakatan Harapan alliance. The bloc is Umno's main rival for power, both in Kedah and at the national level.
The opposition alliance is made up of the PPBM, Anwar Ibrahim's Parti Keadilan Rakyat (PKR), the Democratic Action Party and Parti Amanah Negara. The last is a splinter group that was formed after PAS parted ways with the rest of the opposition in 2015.
Datuk Amiruddin said on Sunday night that he had joined PPBM, and he cited PAS' refusal to cooperate with other opposition parties as the reason for his defection.
The party is now without a recognisable leader in the state, after the former chief minister Azizan Abdul Razak died in 2013.
He said he had asked the PAS leadership to either join the Harapan alliance or work closely with the opposition against the Umno-led Barisan Nasional government. "The response from them was that it would be impossible," he said.
Speaking at the Kedah PPBM headquarters, Mr Amiruddin said: "If we are serious about seeing change and fighting the Barisan Nasional in the next general election, the only way is to stay united and join Pakatan. Staying away and trying to fight the battle alone is not the way."
PAS' ups and downs over the past decade
2007: With former deputy premier Anwar Ibrahim freed from jail and campaigning for the opposition, Parti Islam SeMalaysia (PAS) forms an electoral pact with the rest of the opposition.
2008: The alliance denies Barisan Nasional (BN) its customary two-thirds majority in Parliament and wins five states for the first time. PAS forms Pakatan Rakyat with the Democratic Action Party (DAP) and Anwar's Parti Keadilan Rakyat (PKR).
2011: The issue of hudud, or Islamic criminal code, surfaces. It is close to the heart of PAS, but the DAP opposes it. The coalition decides PAS could continue to campaign for it, but a decision to implement it would need the consensus of all three parties.
2013: The opposition makes further gains in Parliament, as BN loses the majority of votes. But the opposition cannot claim enough seats to form the federal government and even has to cede two PAS-controlled states. With DAP and PKR holding a stronger majority in Penang and Selangor compared with PAS in Kedah, some question if PAS has become a junior member in the coalition.
2015: PAS seeks to regain Malay-Muslim support by tabling Bills to turn hudud into state law. This not only splits Pakatan Rakyat, but also PAS as some leaders leave to form Parti Amanah Negara.
2016: PAS president Abdul Hadi Awang tables a motion to allow Islamic courts to mete out harsher penalties, and Umno allows him to present it in Parliament. Both parties insist they are working to further Islamic interests.
2017: A schism forms in PAS over Datuk Seri Hadi's ties to Umno. Some are uneasy working with Umno and want an arrangement to avoid clashing with the Pakatan Harapan pact comprising PKR, Parti Pribumi Bersatu Malaysia, DAP and Amanah.
The development is the latest in a string of setbacks for PAS since it lost Kedah state in the 2013 election. The party is now without a recognisable leader in the state, after the former chief minister Azizan Abdul Razak died in 2013. His rival for the position at the time, Mr Phahrolrazi Zawawi, has since joined Parti Amanah Negara.
An influential MP, Datuk Mahfuz Omar, was sacked as state chief in 2015, but Mr Amiruddin refused to take over the position, leaving PAS with no choice but to appoint Dr Fakhruddin Fakhrurazi - a largely unknown politician - to the position.
Mr Mahfuz has, so far, dismissed any talk of following in Mr Amiruddin's footsteps. However, he last month welcomed PAS' decision not to endorse him as a candidate for the general election.
Opposition sources, speaking to The Straits Times, said Mr Mahfuz - a former PAS information chief - and members of his faction, including at least one other state assemblyman, will contest the election as Harapan candidates.
Harapan is now the largest opposition bloc in Kedah, with nine assemblymen against PAS' seven. Barisan Nasional, which governs the state, has 20.
Kedah is also home to 15 parliamentary seats, and Pakatan Harapan leaders said the coalition aims to win two-thirds of the seats at the next election in a bid to form a majority.