Sacked Umno man Khairy Jamaluddin has scoffed at calls by Pakatan Harapan (PH) leaders for Muda president Syed Saddiq Syed Abdul Rahman to vacate his Muar seat, saying it is they who should seek a fresh mandate from the people for abandoning their election promises.

"Syed Saddiq is an MP who is sincere about PH's policy platform, which is against cooperation with Umno and (Ahmad) Zahid Hamidi," the former health minister said in the latest edition of Keluar Sekejap, a political podcast he hosts with former Umno information chief Shahril Hamdan.

Khairy said voters in the general election last year had backed PH primarily because of the coalition's stand not to work with Zahid, the Umno president whose corruption trial on 47 charges was suddenly halted following a decision by the government to apply for a discharge not amounting to an acquittal (DNAA).

"People voted for PH in the last election because of Hoi Hoi Ya Hoi," said Khairy, referring to the lyrics of a song targeting Zahid and other Umno leaders facing charges, which had been part of PH's general election campaign.

"So Syed Saddiq is the only one from the PH group today who still adheres to the principle of rejecting Hoi Hoi Ya Hoi, while the others have all embraced Hoi Hoi Ya Hoi. Therefore, those who should resign and seek a mandate from the voters are those from PH, as they have violated their promise to the people," said Khairy.

In the general election last year, Muda entered into an electoral pact to avoid clashing with PH candidates.

Syed Saddiq retained his Muar seat with a smaller majority, winning 19,961 votes, while Perikatan Nasional came a close second with 18,616 votes.

Following his recent announcement of quitting the government bloc, PH leaders had urged Syed Saddiq to vacate the seat, saying it was won on the back of the coalition's support.

The calls grew louder after Syed Saddiq labelled DAP as Umno's lapdog, echoing Khairy's earlier criticism.

The 30-year-old has emerged as one of the most vocal politicians to condemn the move by the Attorney-General's Chambers to halt Zahid's corruption trial, despite the court establishing a prima facie case for the deputy prime minister to enter his defence.

Zahid was instrumental in ensuring Anwar Ibrahim's appointment as prime minister, pledging to bring Umno MPs to back the PH chairman following a hung parliament after the general election.

The DNAA given to Zahid, regarded by critics as part of a series of about-turns by the Anwar government over the last 10 months, had sparked public outrage, with a protest planned in Kuala Lumpur on Sept 16 urging the reinstatement of the criminal charges.

Khairy, who had in the past clashed with Syed Saddiq when they led the youth wings of Umno and Bersatu, respectively, said the Muda president was being bullied by PH cybertroopers who had turned against him.

"I don't like bullies. As if he's the one who doesn't have principles.

"I want to tell PH cytros that the spelling of 'principle' in English is P-R-I-N-C-I-P-L-E, not 'principal,' which means a chief or head of school. So get it right!

"Saddiq is principled. He still adheres to the anti-Hoi Hoi Ya Hoi stance. The rest are all Hoi Hoi Ya Hoi. So if you're asking me to resign and vacate, you vacate your seats first," Khairy added.