The opposition held weeks of protest rallies to demand his resignation for alleged corruption and abuse of power.
Thaksin, who denies any wrongdoing, offered on Monday to set up a reconciliation committee to judge whether he should step down despite receiving what he said were more than half the votes cast on Sunday - his previously announced threshold for staying in power.
The Election Commission was expected to release complete election returns on Tuesday, but Thaksin said preliminary results showed his party won 57% of the votes.
Critics rejected his idea of a reconciliation committee as insincere and called for new anti-government protests this week.
Ong-Art Klampaiboon, the opposition Democrat Party spokesman, said: "The prime minister just wants to find ways to stay in power by finding new marketing strategies and new products."
The comments were an apparent reference to Thaksin's background as a tycoon who made his fortune in telecommunications.
Legal tangles were also likely over the technicalities of balloting that left some districts with no winning candidates because of the opposition boycott, ensuring that Thailand would remain enmeshed in a crisis that has shaken its political stability.
Thaksin's opponents have been holding rallies for more than two months, drawing as many as 100,000 people in efforts to pressure Thaksin to leave office.
Thaksin called Sunday's snap election hoping to gain a fresh mandate from voters who awarded his Thai Rak Thai - Thai Love Thai - party 377 of the 500 seats in the House of Representatives last year.
The three parliamentary opposition parties refused to field candidates and called on voters to show their disapproval of Thaksin by ticking the box on their ballots signifying an abstention.
According to incomplete returns, Thaksin got his victory, but significant numbers of people cast ballots to abstain. With neither side scoring a knockout blow, the political divide may not be easily resolved.