Emmanuel Macron. Pic/AFP

Paris: France's presidential election campaign lurched deeper into uncertainty on Tuesday after centrist Emmanuel Macron was forced to deny an extramarital affair while financial scandal continued to dog conservative rival Francois Fillon and his party. Macron has become the favourite to win by a thin margin since a scandal two weeks ago surrounding the work of Fillon's wife, Penelope, knocked the former prime minister off the top spot.