Former Malaysian Prime Minister Mahathir Mohamad was sacked from the political party that he co-founded.

In a letter to Mahathir on Thursday, the Parti Pribumi Bersatu Malaysia (PPBM) Working Secretary Muhammad Suhaimi Yahya said the former Prime Minister’s party membership was terminated after having sat with the opposition during the one-day Parliament session on May 18, an act that violated the party’s constitution, according to the reports.

Mahathir, who was party chairman, was fired for not supporting Malaysia’s government, which is headed by Prime Minister Muhyiddin Yassin, the Bersatu president.

Mahathir founded the PPBM in 2016 with Muhyiddin after the two fell out with then Prime Minister Najib Razak.

Mahathir and Muhyiddin became PPBM’s chairman and president, respectively.

According to Muhyiddin’s aide, the letters were authentic.

Muhyiddin’s move is being widely seen as an attempt to consolidate power as he faces a possible challenge to his nascent premiership.

In February this year, a day after Mahathir submitted a letter of resignation to Malaysia’s king, the government party rejected his resignation and urged him to continue leading it.

The crisis ended with Muhyiddin, who founded Bersatu with Mahathir before joining a four-party alliance that won 2018 elections, being nominated as the prime minister.

Mahathir, who decided shortly after resigning that he wanted to be prime minister again, bitterly opposed the new government and denounced his former ally as a traitor.

Earlier, Mahathir had ousted then-prime minister Najib Razak, who has been linked to a multibillion-dollar scandal involving a government fund.

Mahathir was prime minister from 1981 to 2003 and was part of the long-ruling party Barisan Nasional (BN). Anwar was his deputy but the relationship soured when Anwar was sacked in 1998 after a leadership dispute.

Mahathir sought a confidence vote in Muhyiddin on May 18 but the parliamentary sitting was restricted to an address by King Abdullah, prompting a furious Mahathir to claim “democracy is dead” in Malaysia.