I would try all cleaners both comercial and residential, but not any distillates or oil derivatives. the vinyl could melt.
409, scrubbing bubbles, etc.
If this does not work and you have exhausted your attempts, consider installing a "kicker" board around your deck that resembles a base board. This is done alot on decks to finish off the deck at the intersection of the home and the deck itself.
Also, you might try some hand cleaner too. I would do all I could quickly before it sets in and before the sun and summer comes. The longer it sits the longer it will stay.