From Longman Dictionary of Contemporary Englishfront-runnerˌfront-ˈrunner noun [countable] COMPETE WITH/TRY TO BEATthe person or thing that is most likely to succeed in a competition the front-runner in June’s presidential election
Examples from the Corpus
front-runner• Recall the dull front-runner, unloved but unavoidable, who plods ahead to victory in his place.• He had predicted he would win the Louisiana caucuses and be a strong runner-up to Dole, the front-runner, in Iowa. 