Adored by millions and reviled by many, Thai billionaire ex-Prime Minister Thaksin Shinawatra has towered over his country's turbulent politics for more than two decades — even though he's lived mostly in self-exile since the army overthrew him in 2006.

Now, Thaksin's announcement of plans to return to Thailand in July has caused a stir as voters prepare to go to the polls in a general election on Sunday, with implications for the vote and the inevitable horse-trading afterward to form a government, analysts say.

Thaksin's daughter, Paetongtarn Shinawatra, 36, is the leading prime ministerial candidate for the opposition Pheu Thai party made up of loyalists to the populist movement that first swept her father to power in 2001.