Brexit: Labour must champion case for remaining in the EU, Tom Watson to urge Jeremy Corbyn
In his speech on Europe at the Centre for European Reform, the deputy leader will also recount a recent conversation he had with Justin Welby, the Archbishop of Canterbury.
"Something he said to me resonated very deeply. He told me that our politicians need to learn to 'disagree well'. I think we all instinctively understand what he means by that," Mr Watson will say. "I will try to make the positive case for what I believe.