Anwar said Wednesday that coalition lawmakers from Malaysia's eastern states of Sabah and Sarawak had contacted him about switching sides, a move that could help shift the power balance and unseat the government.
Anwar's three-party opposition coalition won more than a third of parliamentary seats and four states during the March 8 election.
Prime Minister Abdullah Ahmad Badawi denied Anwar's claim that the ruling National Front coalition is falling apart and plagued by infighting.
His new 69-member Cabinet was sworn in Wednesday, nearly two weeks after the ruling coalition suffered major losses in the elections.
On Tuesday, the prime minister slashed the 90-member Cabinet in a bid to rejuvenate his administration.
Among those dropped was Home Minister Radzi Sheikh Ahmad. Radzi Wednesday resigned his posts as secretary-general of the National Front and head of the United Malays National Organization. The UMNO is the major party in the ruling coalition.