I think that 1 Ra8+! draws. Let's see what I think is the critical variation:1...Kg7 (the Black King tries to attack the White rook) 2 Rg8+ Kh7 (2...Kf6 3 Bxa2= and we get a position of R+N vs R in which all the White king has to avoid is being driven to the edge of the board) 3 Bxa2! Rxa2+ and here I first thought 4 Kb3 made it but black has 4...Rb2+ winning. Has White any salvation in this position? What about 4 Kb1! and now if 4...Rb2+ 5 Ka1! and the White Rook cannot be taken because of stealmate!
I meant 1 Rh8+!
It doesnt work either, Black has 4...Nc3+ ...sorry guys.
Hey, one moment, what if 5 Kc1! and we are again in a position of stealmate! 5...Ra1+ 6 Kb2=