OK - I have looked, played with the melody, and finally came to the conclusion...
there are similar songs out there, but I'm not finding a direct translation of this chorus... so I took a little liberty with the literal meaning and went for the heart of the meaning...
thoughts?
here is the English that our church sings:
Oh, the blood of Jesus
Oh, the blood of Jesus
Oh, the blood of Jesus
It washes white as snow
(now, since 'nieve' is an awkward 3 syllable word, I went for this
Ah, la sangre de Jesus
Ah, la sangre de Jesus
Ah, la sangre de Jesus
Deja blanco al pecador
(It washes the sinner white)
(Edited with thanks to Lrclaros)