Mr Najib is riding a good economy into the election. The ringgit has been one of Asia’s strongest currencies, stocks have hit a two-year high, and economic growth was 5.6% in the first quarter.

And an opposition victory, however unlikely, would put Malaysia into uncharted waters and likely trigger fears of a short-term plunge in financial markets.

Analysts say the entry of Malaysia’s former prime minister Mahathir Mohamad into the electoral fray supporting an Anwar Ibrahim-led opposition alliance represents a real threat to UMNO.

“If the two leaders can revive a reversed role of their previous partnership displayed so effectively when they were in national leadership in the 1990s, the opposition could have a winning formula,” said Yang Razali Kassim, senior fellow at S. Rajaratnam School of International Studies in Singapore.