Jailed former prime minister Najib Razak's graft-tainted party is seeking to cement its grip on power as the country goes to the polls on Saturday, but analysts say the race is too close to call.
Umno usually dominates politics in the country, but suffered a major defeat in the 2018 general election after a massive corruption scandal at state fund 1MDB.
The two governments that succeeded Umno, however, were plagued by infighting, allowing the party to creep back into power last year. Now, Umno will be seeking a stronger mandate in an election called ten months ahead of schedule.
Among the challengers is perennial opposition leader Anwar Ibrahim, 75, who leads the ethnically-diverse Pakatan Harapan (PH) coalition. He is campaigning on an anti-corruption platform.
With age catching up, this election could be Anwar's last chance to fulfil a 20-year dream to lead the country.
He is up against the ruling Barisan National (BN) coalition, which is dominated by Umno and led by Najib loyalist Ahmad Zahid Hamidi. It also includes Prime Minister Ismail Sabri Yaakob.
Umno remains hobbled by corruption allegations. Najib, who was at the centre of the 1MDB scandal, is currently serving a 12-year jail term.
Opposition parties say they are concerned the ex-prime minister could walk free and corruption charges against Zahid and other party leaders could be dropped if Umno wins.
Former prime minister Dr Mahathir Mohamad, 97, and another ex-leader Muhyiddin Yassin, 75, head two other coalitions contesting the elections.
'Fragmented political landscape'
Analysts said there was no clear frontrunner among the four coalitions seeking the 222 parliamentary seats at stake.
Malaysians will choose from a record 945 candidates across the nation, which also includes the states of Sabah and Sarawak.
"Voters can expect a plethora of candidates on their ballot papers, such that they will have a hard time deciding between candidates with similar positions," said Oh Ei Sun of the Pacific Research Center of Malaysia.
The number of eligible voters has risen from 18 million four years ago to more than 21 million, after the voting age was lowered in 2021.
About 1.4 million of the new additions are first-time voters aged between 18 and 20.
The majority of voters live in rural areas, where patronage politics continues to hold sway.
Analysts said the multiracial country would be in for further political instability if no coalition wins a clear majority.
"Unless PH can clinch an outright parliamentary majority... the dominant Umno party or one of the Malay Muslim parties would get to form a coalition government," Oh told AFP.
"Voters are likely to look forward to a similarly fragmented political landscape after the election, with a lot of horse-trading to form the next ruling coalition."
The election comes as Malaysians face soaring food prices, and parts of the country continue to be battered by flash floods due to monsoon rains.