That's a tough call.....Personally, i think i would check it to the raiser. If he (and everyone else) decides to check, maybe you hit your straight.
If he comes in for a medium sized bet, i would come over the top with a relatively large raise, to see how good he feels about his hand.
However, if he comes out guns ablazing and bets really big, or even all-in, i would be much more cautious. While he could be on a draw, you aren't going to get him out of this pot. If everyone else folds, i would consider calling, but if he gets a caller ahead of you, i'm out of there.
Tough play though. Could go many directions