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After nearly three decades of autocratic rule, Cambodia's Prime Minister Hun Sen may be facing his biggest political dilemma in years, with his party's parliamentary majority vastly eroded in weekend elections by a burgeoning opposition that could block his forming a government.

But the farmer's son whose favorite pastime is chess may still have some unexpected moves in his game.

After all, Hun Sen has already successfully bested the communist Khmer Rouge, the country's king, the international community and all political rivals big and small.

The opposition could block Hun Sen from forming a government, and whether he will use the carrot or the stick to break such a deadlock is not yet clear — since he hasn't spoken in public since the polls.

With unchallenged authority over the bureaucracy and the security forces, he is likely to prevail in the end. But a forcible solution could come at the cost of unrest and violence. Sweeping all the chess pieces off the board would damage the softer, statesman's image he has been promoting in recent years.

Opposition leader Sam Rainsy, recently returned from exile, is demanding an independent investigation of alleged widespread irregularities in Sunday's polls. Beyond suggesting that it might ask for recounts or a new vote, the opposition hasn't declared what it might do. But legal experts say it could block the opening of parliament by not showing up and denying the assembly a quorum.

The unexpectedly strong showing by Rainsy's Cambodia National Rescue Party seems to have punctured the aura of Hun Sen's invincibility.

"He is humbled and humiliated," said Lao Mong Hay, an independent political analyst. "He has lost much credibility and legitimacy. He may put up a brave face, acknowledge his weaknesses and wrongdoing in public, and continue to lead his government," perhaps sharing more power with party colleagues.

Humbled or not, Hun Sen isn't expected to back down. His style was analyzed in a 2009 U.S. Embassy cable released by WikiLeaks.

"When CPP leaders perceive a choice between pluralistic liberal democracy and order, stability and economic development, they will exploit that conflict to maximize their own power and pre-empt opposition challenges to their political authority," it noted.

The cable, sent in the name of then-Ambassador Carol Rodley, also pointed to "a familiar pattern of post-election crackdowns seen in 1995, 1998, and 2005," while noting "much reduced violence, (and) the more sophisticated curtailment of wide-open freedoms."

Hun Sen nowadays harasses his opponents in the courts, which have a reputation for being under the government's sway. Overt violence has not disappeared, but no major incidents or murders were reported in this year's campaign.

Opposition leader Rainsy was a target of the legal approach, going into exile in late 2009 to avoid a jail sentence of 11 years on charges he said were politically concocted.

Hun Sen's engineering a royal pardon so Rainsy could come back for the last week of campaigning — while remaining off the ballot — shows his touch for the ostensibly generous gesture, though some wonder if his timing was uncharacteristically off, allowing opposition momentum to peak on election day.

Hun Sen now finds himself engaged in a game of who blinks first, as the opposition is united in a way it has never been before and can point to the strong support it won from the voters.

He could seek to open parliament through a legal loophole, though such a move would support charges of unfairness and high-handed behavior. His party and the government-appointed National Election Committee have suggested in the past that if the opposition would not take their National Assembly seats, they could be distributed to other parties, said Astrid Norén-Nilsson, a Cambodia scholar at the University of Cambridge. She added, however, that she believed it would now be more difficult to carry out that threat in view of the opposition's proven popularity.

"We could see quite a lengthy period of bargaining between the CPP and CNRP," she said, pointing out the opposition's newly demonstrated power. "However, I think that it's likely in the end that the CNRP will accept the results of the election in line with the figure we have seen now, simply because this result is a quite good increase for the opposition" to begin trying to institute change.

Hun Sen could try to wait out his opponents as head of a caretaker government. In past elections, he has managed to lure defectors from other parties, though he would need many more this time. And he can bide his time before taking more radical measures, such as expelling opposition MPs from parliament, as the ruling party did just before campaigning began.

Cambodia faced a similar situation after its 2003 election, when Hun Sen's party failed to win enough seats to form a government on its own. The deadlock was broken only after 11 months and the mysterious deaths of several opposition activists.

But Hun Sen faced a divided opposition then, able to persuade one of the parties in the opposition to share power. Today, the opposition represents only one party and it is energized.

Hun Sen does not have a record of accepting setbacks gracefully, and he has long proved capable of making daring decisions, starting with his 1977 defection from the Khmer Rouge, two years after they took over Cambodia and were carrying out bloody purges within their ranks. The timely change of sides led to his being appointed foreign minister, then prime minister, by the Vietnamese forces who in 1979 ousted the Khmer Rouge.

Since then, for all practical purposes, he has never left the top post, even as a U.N. peacekeeping force and the late King Norodom Sihanouk tried to assert their authority. When his party came in second in the 1993 U.N.-supervised election, he won a position of co-prime minister by threatening civil war.

Just four years after that, he deposed his partner in government in a bloody coup d'etat, and he hasn't looked back since.

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Peck reported from Bangkok, Thailand.