Lib Dem frontbencher David Heath has confirmed that he will vote against the Lib Dem whip and for a referendum on the EU Constitution. Nick Clegg now faces a difficult choice. He can sack Heath and show that he will not back down from enforcing party discipline. However, this approach would highlight the Lib Dem’s breach of their manifesto promise to support a popular vote on the EU Constitution. Or, he can let Heath get away with defying the party line and create a precedent that will wreak havoc on party discipline. Two factors are likely to make up Clegg’s mind. First, whether the Lib Dems can succeed in getting their amendment on an in or out referendum down and second how many Lib Dem MPs look like following Heath’s lead.