The phrase "potential frontrunner" means someone or something that has a good chance of being in the lead or winning in a competition, but it is not certain yet. Full definition
Mario Cuomo was considered a potential frontrunner for the Democratic presidential nomination in 1988 and 1992, but decided not to run both years. (newyork.cbslocal.com)
The Shape of Water, a tale of a mute woman (Sally Hawkins) who falls in love with an amphibious being trapped in a government lab, has been praised for its allegorical import by critics and is positioned as a potential frontrunner at the upcoming Oscars. (theatlantic.com)