Rome, November 26 - Democratic Party (PD) Secretary Pier Luigi Bersani is set to take on Florence Mayor Matteo Renzi in a runoff in the primary to select the centre-left's premier candidate next weekend after none of the contenders won more than 50% in Sunday's first round. As expected Bersani, a former industry minister, was on course to finish top in the first round with 44.9% of the votes, with most of the results counted early on Monday. Renzi, a 37-year-old who presents himself as a modernizer, was second with 35.5%. The winner of the primary has a good chance of being Premier Mario Monti successor as the PD are leading in the opinion polls ahead of next spring's national elections. Nichi Vendola, a gay left-winger who is the governor of Puglia and leader of Left, Ecology, Freedom party that is poised to run in coalition with the PD at next year's elections, was third with 15.6%. Laura Puppato, a businesswoman and PD councillor in the Veneto regional assembly, and Bruno Tabacci, a member of the centrist Alliance for Italy party that is also set to run in coalition with the PD, came a distant fourth and fifth with 2.6% and 1.4% respectively. The fact that over three million people voted in the first round of the primary was hailed as a big success for the centre-left by the candidates and by political pundits.