By Matt Siegel ADELAIDE, Australia (Reuters) - As Australians cast their ballots in a tight election on Saturday afternoon, senator Nick Xenophon worked up a sweat while preparing kebabs at a Greek restaurant in his hometown. "Nick, if you no get across the line tonight, I give you a job," owner Yianni Tsagariolis shouted in a thick Greek accent, drawing laughter from Xenophon supporters who had gathered at the restaurant. Australians went to sleep without knowing who will be prime minister, but the eventual election winner -- whether the ruling conservative Liberal-National coalition or the opposition Labor Party -- will likely need to negotiate with NXT senators to pass key legislation.