Abdullah has also seen his support eroded by growing racial and religious tension as Malaysia's minority ethnic Chinese and Indian communities fear their rights are being trampled on.
Ethnic Malays, who are mainly Muslim, make up just over half of Malaysia's 26 million people, with ethnic Chinese accounting for a quarter and Indians around 7 percent.
The government was alarmed when more than 20,000 people turned out in November for two protests, one by opposition parties demanding poll reform, and the other by ethnic Indians complaining they had been denied job and education opportunities.
Abdullah's ruling coalition runs no risk of losing the polls but it is likely to see its majority reduced, analysts say. If Anwar can tap into the minority groups' unhappiness, their disaffection could be the astute politician's greatest asset.
"We have the minorities being angry. They are really angry," Anwar said. "But of course I don't take things for granted," he added, vowing to shape his party's agenda and list of candidates carefully in order to lure minority votes for the opposition.
Born on August 10, 1947, the son of a politician, Anwar went to one of Malaysia's top schools, the Malay College in the royal town of Kuala Kangsar, and made his name as a firebrand Islamic youth leader.
He was jailed for 20 months under the Internal Security Act beginning in 1974 for leading anti-government demonstrations against impoverished conditions in the north.
Mahathir invited him to join UMNO in 1982 and Anwar began a meteoric rise. He held a string of senior cabinet posts, including the ministries of agriculture and education, and had been finance minister since 1991 before being sacked.
Anwar was sentenced to a total of 15 years in jail for abuse of power and sodomy - charges he said were fabricated by Mahathir's government to prevent him challenging the ex-premier.
Mahathir denies the accusations, saying he sacked Anwar because he was morally unfit to rule.
Anwar was removed in the midst of Asia's financial crisis, which opened up a rift between Anwar and a business elite close to Mahathir, who retired in 2003 after 22 years in power.
Anwar is married to former eye doctor Wan Azizah Wan Ismail. The couple have six children, five girls and a boy.
