https://www.bbc.co.uk/news/uk-northern-ireland-47718367
Meanwhile, leading Brexiteer Jacob Rees-Mogg has said he will only back the government's Brexit deal if the DUP does.
On Tuesday, he had hinted he could back the prime minister's plan, at the risk of there not being any Brexit at all.
But in a piece for the Daily Mail, he said his support is conditional on the DUP's decision.
So far, the DUP has not indicated that it is prepared to back the government's deal unless there are changes to the Irish border backstop.
On Tuesday, Sammy Wilson, the party's Brexit spokesperson, said a long delay of up to a year would be preferable to the deal.
But the DUP said its position as a whole remains unchanged.