REGIONAL Councillor Alfred Tso Shiu-wai looks set to win today's by-election to the Legislative Council to take up the seat vacated by convicted vote-buyer Gilbert Leung Kam-ho. Mr Tso, a member of the Liberal Democratic Federation, is backed by rural and pro-China groups, which have 18 and three votes respectively, for the Regional Council functional constituency. His rival, independent councillor Yeung Fuk-kwong, conceded yesterday that Mr Tso stood a better chance of winning the seat than either him or the two other candidates - independent Lau Kwong-wah and United Democrat Chow Yick-hay. Mr Yeung estimated he would get three to five votes in the first round of the election. One regional councillor said the conservative, rural grouping would control the election. The grouping consists of members of the Heung Yee Kuk (the New Territories landlords' body), the rural committees and other associations. ''The rural forces are very united when it comes to elections,'' he said. The Reverend Fung Chi-wood, a member of the United Democrats' central committee, said the result would be very difficult to predict because of the complicated voting procedures. The electors - the 35 Regional Councillors - mark down the candidates in order of preference. If one candidate secures more than half the first preference votes he is elected. But if no-one secures an absolute majority in the first round, the candidate with the least number of votes is eliminated and the votes transferred to the other candidates according to the next preferences shown on his ballot papers. Mr Fung admitted his party colleague Mr Chow stood only a slim chance of winning because of the distribution of power in the Regional Council. ''It would be an unexpected gift to us if he gets the seat, but it is worth running,'' he said. Mr Tso was confident yesterday, but refused to predict the number of votes he will get. He believed the rural forces in the Regional Council were united and some of the members had indicated they would vote for him. At an election forum yesterday, the candidates were split over whether Governor Chris Patten's political reform proposals should be tabled in the legislature, despite opposition from China. Mr Tso said he would definitely object to the proposals if they were tabled in the Legislative Council in the form of a bill. ''Although it is important to speed up the pace of democratisation, Hongkong also needs stability and prosperity. After all, Hongkong is not an independent political entity.'' He said the Basic Law had outlined the political development and Hongkong people had had few objections during the consultation period. But Mr Lau disagreed, saying Hongkong people had expressed dissatisfaction with the Basic Law. Mr Lau, a former United Democrat, said many people would like quicker democratisation which the Basic Law could not fulfil. He said he would consult his electors before deciding how to vote. Gilbert Leung was convicted on June 1 of buying votes and was sentenced to three years in jail. He was automatically disqualified from all his elected positions. CANDIDATES LINE UP: CHOW YICK-HAY, 35, a United Democrat who attempted to enter the legislature in 1991 through the Regional Council functional constituency, but lost in the third round of voting. He is an administrator at the Chinese University and an elected Kwai Tsing District Board member. LAU KWONG-WAH, 36, a lecturer at the Hongkong Polytechnic who quit the United Democrats this year after failing to be elected to the Legislative Council in the September 1991 direct election. He is an elected Sha Tin District Board member and an Airport Consultative Committee member. YEUNG FUK-KWONG, 40, a solicitor, tested his popularity in the New Territories South constituency in the 1991 poll, coming last out of four candidates. He is an elected member of the Tsuen Wan District Board and is also a member of the Progressive Hongkong Society.