Mr Thaksin still enjoys wide support among poor, rural Thais
Thailand's ousted Prime Minister Thaksin Shinawatra has called for an end to "interference" in Thai politics.
His demand - apparently a reference to senior military and royalist figures - was made in a video message to a party rally at a Bangkok sports stadium.
Mr Thaksin is in self-imposed exile after being convicted of breaking conflict of interest rules.
Parliament is voting on Monday for a new prime minister to succeed his brother-in-law.
Mr Somchai Wongsawat was forced to resign by a court ruling earlier this month.
The court found his party, the People Power Party (PPP), guilty of fraud during the last election a year ago, and banned it and two other parties in the governing coalition.
They have now regrouped under new names, but the opposition Democrat Party says it has won over enough defectors and unaligned MPs to lead the new government.
Opposition protests
An estimated 40,000 people filled the stadium on Saturday afternoon, police said, ahead of Mr Thaksin's address.
Those people who interfere in forming the government must stop and withdraw
Thaksin Shinawatra Ex-prime minister
Speakers poured scorn on the defectors who have given the opposition Democrat Party its first shot at forming a government in eight years.
In a pre-recorded video address, Mr Thaksin demanded that those forces which he said had been meddling to undermine the government led by his allies should stop.
The BBC's Jonathan Head in Bangkok says this was a thinly-veiled reference to senior military and royalist figures who have been backing Mr Thaksin's opponents.
Plans for a live telephone link to the rally were abandoned at the last minute, organisers said, and our correspondent says Mr Thaksin's address failed to live up to expectations.
Thaksin sends message to supporters
He spoke of his sadness of being stuck in exile and over recent events in Thailand and talked of Thai society being stabbed in the back.
He condemned the outside forces, presumably the army and figures close to the palace that had meddled to bring down free governments led by him and his allies, our correspondent notes.
But Mr Thaksin made no attempts to win back the defecting MPs and - assuming they stand firm - the Democrats should win enough votes in Monday's special session of parliament to form the next government.
The Democrats, who were defeated in the last general elections in December, will propose to parliament that Abhisit Vejjajiva becomes the next prime minister.
The new prime minister would be the country's fifth leader in a little over two years.
Thailand has been in political deadlock for months as anti-government protesters have mounted a campaign to remove the governing party.
They accused the PPP of being a proxy for Mr Thaksin, who was ousted in a military coup in 2006.
The protest culminated in a week-long occupation of Bangkok's main international airport that left 300,000 foreign tourists stranded.
The opposition called off its action after the recent decision by the constitutional court to disband the PPP.
Our correspondent says that after months of turmoil, Thailand is now just days away from a new government that just might be able to cool the political atmosphere.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.
Bookmark with:
What are these?