After nearly three decades in power Cambodian strongman Hun Sen no longer bothers with election campaigning, but an opposition rejuvenated by the return of its leader from exile is battling back. Former Khmer Rouge fighter turned prime minister Hun Sen has run the country almost single-handedly for 28 years, and has vowed to stay in power for at least another decade. From near-total control of the country’s newspapers and television to a pliant bureaucracy and a deep campaign war chest, Hun Sen’s ruling Cambodian People’s Party enjoys all the advantages of its decades-long monopoly on state power. But following years of infighting, the main opposition groups have united and - galvanised by the return from exile of their recently pardoned leader Sam Rainsy - are bringing some real competition as Cambodia heads towards Sunday’s parliamentary elections. “Hun Sen is more nervous than before,” said political expert Lao Mong Hay, a former researcher for the Asian Human Rights Commission. “You can see he’s using threats and intimidation,” he said, adding that such tactics are becoming less effective. “Cambodian people are no longer easy to rule, especially the young,” Hay said. One of Asia’s longest serving rulers, Hun Sen, 60, has been in power since 1985 and his Cambodian People’s Party has increased its majority in every poll since 1998. But its absolute majority - it has 90 seats in the 123 seat parliament - could now be under threat from the opposition Cambodian National Rescue Party (CNRP), observers say. “There is no doubt that the opposition is more united and organised than ever before,” said analyst Jackson Cox of consultancy firm Woodmont International. “The support in the streets for the opposition CNRP is palpable.” Even so, it was “hard to imagine them unseating the CPP,” he added. The CPP oversaw Cambodia’s transformation from the ashes of war to one of Southeast Asia’s fastest growing economies, with a flourishing export-orientated garment sector and soaring foreign direct investment. But rapid growth has brought with it rising discontent over low pay and poor conditions in factories, vast land concessions to foreign firms and land grabbing by a powerful elite. While the CPP-dominated mainstream media was mute on the estimated 100,000-strong crowd that turned out last week to welcome Rainsy home, social media is allowing the opposition to share campaign news and reach out to young, urban voters. But in a country where Internet penetration is between three and five per cent, it still struggles to reach much of the population. For decades, Hun Sen’s simple message - that he and the CPP liberated Cambodia from the Khmer Rouge and ushered in decades of peaceful development -- has been enough to guarantee support. “I have voted for the CPP since 1993... they have developed the country and most importantly they secured peace,” Pov Dep, a 57-year-old farmer from southwestern Prey Veng province, said. But analysts say another major reason for the party’s enduring success is widespread voter intimidation, systematic vote-buying and an electoral system heavily biased towards the ruling party. With the opposition now flying high, “all the tricks are being pulled out this year” and the chants of “change” from Rainsy supporters may go unanswered, said Naly Pilorge, director of the Cambodian League for the Promotion and Defence of Human Rights. Voter registration in some areas -- particularly where the opposition is strong - is well over 100 per cent, which coupled with the unusually high use of temporary voter identity papers hints at fraud, election watchdogs say. “In terms of a level playing field -- for media access, use of state resources during campaigning, restrictions on the opposition -- it’s worse” than in previous elections, Koul Panha, executive director of the Committee for Free and Fair Elections in Cambodia, told AFP. The CPP has also been using state employees to campaign, including judges and prosecutors, and vote buying is “systematic”, he said. The National Election Committee, which organises the poll, said it had seen no evidence of any major irregularities. But the NEC is also heavily biased towards the ruling party, said political activist and radio station owner Mom Sonando, who has spent multiple spells in prison and was described as a “prisoner of conscience” by Amnesty International. If the poll was free and fair, Sonando believes Hun Sen would lose. “People have suffered for a long time... now the people are standing up,” he said.