The Bill was given an unopposed second reading after a seven-hour debate in the Lords, in which more than 60 peers spoke.
But there were warnings from Labour and Liberal Democrat backbenchers that the legislation, which guarantees a vote on EU membership in 2017, could be delayed and fail to make it back to the House of Commons in time to become law.
The plan to table amendments to the European Union (Referendum) Bill, meaning it could run out of parliamentary time.
James Wharton, the Tory MP who started the legislation as a Private Member's Bill, said that they could try next year if this happened.
The legislation will now progress to committee stage, where it is highly likely amendments will be tabled.
If any amendments are made that MPs want to reverse it must return to the Commons by February 28.
The Government can ask for further sitting Fridays beyond that date, but the Lib Dems are not supporting the Bill.