Early on in the year, it looked like Lady Gaga had Best Actress in the bag. A Star is Born hit strong, much stronger than The Wife. Over time, A Star is Born has cooled off a bit, particularly following its near shut-out at the Golden Globes. Glenn Close, as a result, has risen back into the conversation as a front-runner.
Nothing is certain, however, and an acting front-runner cannot truly be claimed as a true front-runner until they pick up the SAG award. Until that time, we can only speculate.