rome italy anti-establishment 5-star movement lead opinion poll ahead national election due may next year friday launch internal ballot choose leader candidate prime minister hot favorite 31-year-old low house deputy luigi di maio party high-profile popular politician make secret want job appear rival worry big problem maverick movement found eight years ago may find credible alternative candidates contest take form online vote 5-star members line credo direct democracy di maio deputy speaker chamber deputies consider good communicator one 5-star moderate figure post 5-star official mouthpiece blog founder beppe grillo say candidate prime minister would also party leader something always case italian politics grillo found 5-star 2009 far act de facto chief though never run office party always pride horizontal structure official leader person consider realistic threat di maio fiery deputy alessandro di battista give indication plan run another deputy see potential challenger roberto fico represent leave wing party recently distance di maio tough position law-and-order immigration also yet make move post grillo blog say 5-star local national representatives wish run monday present candidacies time online vote yet set winner due announce sept 23 5-star annual national meet adriatic coastal town rimini italy 's 5-star launch vote leader di maio hot favorite