THE Democratic Labor Party's John Madigan will oppose legislation on same-sex marriage and a carbon tax after he takes up his senate seat in July.But a political expert said Mr Madigan, a Ballarat blacksmith, will be virtually powerless, with the Greens set to hold the balance of power.Yesterday the final results had not yet been declared but Mr Madigan is considered likely to gain the sixth Victorian Senate seat, edging out Family First's Steve Fielding and the Liberal Party's Julian McGauran.La Trobe University politics lecturer Ian Tulloch said the Greens would hold nine senate seats, easily outnumbering Mr Madigan.''He's got no power, he doesn't hold the balance of power. He's in a pretty poor negotiating position,'' Mr Tulloch said.The DLP split from the Labor Party in Victoria in the 1950s and retained a strong Catholic support base. The party disbanded in 1978 but was later revived. Peter Kavanagh was elected to Victoria's upper house in 2006.Mr Madigan said if he was elected his senate seat would allow him to drive parliamentary debates on important issues.''If it's confirmed and we are elected, we'll do our very best to give people a voice in the parliament and contribute to an informed and factual debate,'' he said.Mr Madigan said he would oppose gay marriage and the sale of public infrastructure such as Queensland's train system.''Our position is that marriage is between a man and a woman to the exclusion of all others,'' he said.Mr Madigan said the DLP supported measures to reduce the human impact on the environment but opposed a carbon tax.''We're not in favour of a carbon tax because we believe it's a tax on people and a tax on life,'' he said.DLP federal president David McCabe said Mr Madigan could raise the party's profile even though his Senate vote was likely to have little effect on the passage of legislation.The Courier contacted Mr McGauran but he declined to comment until after the result is officially declared.