Canada's three opposition parties are threatening to bring down the minority Liberal government unless it agrees to hold an early general election.
Mr Martin was exonerated in an inquiry into misspending
Prime Minister Paul Martin's office has so far refused, which means he could face a no-confidence vote next week.
The government has been vulnerable since an opposition party withdrew its support in parliament two weeks ago.
It has been dogged by allegations of irregularities over contracts awarded by a previous Liberal administration.
Mr Martin is not implicated in the scandal, but the opposition says his government is tainted and should be forced out of office.
The prime minister has promised to hold an election by April 2006, but correspondents say the opposition parties are concerned that public anger over the allegations of corruption may dissipate by then.
The Conservative Party, the New Democratic Party and the Bloc Quebecois held a joint news conference on Sunday to announce their backing for early general elections.
"I don't believe this government has the moral authority to govern," Conservative leader Stephen Harper said.
The opposition will present a motion this week to hold elections in February.
If the government refuses to debate it, or rejects its outcome, the opposition could bring it down as early as next week, triggering elections in January.