Mary Landrieu’s only chance is to win outright in the primary:
Two polls predict Senate runoff, but differ in support for Mary Landrieu and Bill Cassidy ~ Bruce Alpert
Meantime the statistical gurus over at FiveThirtyEight have increased Bill Cassidy’s chances of winning to 79% with their latest simulation (Election tab). Drilling down on the polling data shows that many of the polls in the Louisiana Senate race are from C rated pollsters though Suffolk University, which conducted one of the latest Louisiana Senate polls is B rated. All the polls line up with Landrieu losing to Bill Cassidy, the main difference being in victory margin.