The Democrat Party and the People's Alliance for Democracy (PAD) say they are prepared to form an alliance to fight the amnesty bill and the Thaksin Shinawatra-backed government.
Democrat MP for Phatthalung Nipit Intarasombat and PAD spokesman Parnthep Pourpongpan have confirmed they are discussing the possibility of working together.
Mr Nipit, accompanied by Democrat secretary-general Chalermchai Sri-on and Democrat MPs Kasit Piromya and Kalaya Sophonpanich, met Mr Parnthep on Thursday.
Mr Nipit said both sides seem to understand each other better and from now on expect to work together to fight what they called the "Thaksin regime".
He said it was agreed that a lack of unity among various groups is weakening the anti-Thaksin movement.
However, he said both sides have certain limitations.
Mr Nipit said PAD leaders facing charges from past political unrest are unable to join political rallies due to their bail conditions, while the Democrat MPs cannot resign to join a street protest.
However, he said these issues should not prevent them from joining hands in their common goal.
He said he had informed senior Democrats of the discussion.
On his Facebook page, Mr Parnthep conveyed PAD leader Sondhi Limthongkul's proposal urging the Democrat MPs to resign and join the street campaign during the meeting.
He said no conclusion was made and the Democrat Party was expected to consider the PAD leader's proposal.
Meanwhile, a group of Pheu Thai MPs led by Weng Tojirakarn is seeking changes to the amnesty bill proposed by Worachai Hema to cover political offences since Jan 1, 2005.
The bill, which was passed in the House's first reading, seeks to absolve political offenders charged with or convicted of offences related to political unrest from Sept 19, 2006 to May 10, 2011.
Mr Weng said the changes are being sought to Section 3 of the bill to grant amnesty to political offenders from Jan1, 2005 to the day that the bill is published in the Royal Gazette.
The Pheu Thai MP said the emergency decree had been invoked several times since January 2005.
He said the bill, after being revised, will benefit thousands of people who allegedly violated the decree.
The revision is to ensure equity for all groups while insisting that protest leaders and decision-makers will not benefit from the bill.
"We want others to know that we are not discriminating against demonstrators wearing other [political] colours," said Mr Weng, who is also a red-shirt protest leader.
"Political conflicts started before the military coup."
He insisted that he and several others who were charged in connection with red-shirt protests would not benefit from the bill.