Labour and the Lib Dems will, of course, vote against the amendment but up to 100 Tory MPs are expected to vote for the amendment which wouldn't result in a referendum, even if it had a hope of passing.
Some Tory rebels are calling for legislation in this parliament for a referendum in the next parliament. Indeed, at the election count in Shrewsbury this month, Daniel Kawczynski MP declared himself a eurosceptic and then told me that David Cameron would pass a law to give us a referendum in the next parliament. I reminded him that under our constitution no parliament may bind its successor and that when the Tories lose the next election Labour would simply repeal the law and no referendum would be held.
He said he would have to ponder that which is a little worrying as I'd expect an MP of 8 years to understand one of the most important principles of parliamentary sovereignty. He was also unaware that the EU referendum bill that was already introduced this parliament has been quietly dropped but his response was that he is a "dyed in the wool Conservative" so it seems that party comes before country for Comrade Kawczynski.
The only way to guarantee a referendum on our membership of the EU is to hold it in this parliament. Cameron knows this which is why he wants to give us another Cast Iron Guarantee™ in his manifesto for the next parliament so that it need never be held. Cameron says that he can't hold a referendum in this parliament because it wasn't in the coalition agreement but neither was same sex marriage. Where there's a will there's a way which is precisely why David Cameron will never deliver an EU referendum.