Andy and Brenda were the best tonight, and have been very consistant throughout the live shows, so I think they are pretty safe.
Maria has been up there, but has now had two pretty average weeks - if there is a surprise act in the bottom 2 it may well be Maria, although I hope not.
Chico seems the most likely candidate, being as he can't sing a note, but he has clung on by his finger nails week after week, so who knows...