The two MPs of Samoa's ruling HRPP party who recently resigned from the government have reportedly met other government MPs opposed to the proposed road use switch.
The government wants to pass a law to change to driving on the left side of the road.
The meeting was reportedly held last week as parliament is due to meet in three weeks time to debate the road traffic bill further ahead of a final reading.
Our correspondent says according to a source in the ruling party, the Prime Minister is facing a testing time amid rumours of more government MPs planning to side with those opposed to the change.
The prime minister's speech in parliament on the subject has been broadcast on television again.
Political observers say this is a sign of pressure being faced by the government over the road switch issue.