An Umno division leader is the latest to express disappointment with Dr Mahathir Mohamad for asking voters to reject BN in the upcoming by-elections.

Syed Ali Alhabshee admitted that he never imagined the former premier would go to this extent since the latter had been a part of Umno for a long time.

"This is perhaps because of his hatred towards (Prime Minister) Najib (Abdul Razak)," he added in a blog post.

The Cheras Umno chief said some believe that Mahathir had been influenced due to personal elements.

Whatever the reasons, Syed Ali said it was not proper for Mahathir to behave like a "spokesperson" for the opposition.

"I was told that many, especially at the Umno grassroots level, are extremely disappointed with Mahathir for portraying himself to be an opposition spokesperson to counter Umno in the Sungai Besar and Kuala Kangsar by-elections," he added.

Furthermore, he said the opposition parties did not make Mahathir their representative to campaign for them in the two by-elections.

He also cautioned that doing so would soil Mahathir's image as a former prime minister.

Syed Ali said he is concerned that people would accuse Mahathir of asking voters to reject Umno, when those close to him are still members of Umno.

The Umno man also described Mahathir's remarks as a personal view, which would not influence the voters in both the constituencies.

He said there is also no reason for the voters to back opposition candidates as the late Umno MPs had excellent track records.

Apart from Umno, Mahathir’s remarks also drew criticism from one of his ardent supporters, former law minister Zaid Ibrahim.

He argued against the rationale of asking voters to reject BN, which could lead to PAS winning the two seats.

The by-elections, which would be held simultaneously on June 18, were called following the deaths of Noriah Kason (Sungai Besar MP) and Wan Mohammad Khairil Anuar Wan Ahmad (Kuala Kangsar MP) in a helicopter crash in Sarawak.