MANCHESTER, England — Boris Johnson will present a "final offer" alternative Brexit deal to the EU on Wednesday, Downing Street officials said, as the British prime minister prepares for his set-piece party conference speech to the Conservative faithful.

The prime minister has insisted he is pushing for a deal with the European Union but he is running out of time after promising to deliver Brexit by October 31 "do or die." Johnson now hopes to shift the focus back onto his efforts to "get Brexit done" — as the party's new slogan pledges — and to rally his troops ahead of a possible election that he hopes will be called in the coming weeks.

Johnson will tell party's annual gathering that the plan, which outlines the U.K. alternative to the Northern Ireland backstop plan, is a "fair and reasonable compromise."

The U.K. plan will be set out in what Downing Street is describing as new, legal texts. The EU has long demanded clarity on U.K. proposals for replacing the backstop, which was designed to avoid a hard border on the island of Ireland, but has so far received only discussion points known as non-papers.

Johnson's speech in Manchester will reiterate his insistence that a deal must be done now before the current legal deadline of October 31, or he will seek to take the U.K. out of the EU without an agreement on that date — despite a law recently passed by MPs that blocks him from doing so.

British officials indicated that if the EU does not negotiate on the basis of the new proposals, which have yet to be outlined in detail, then talks will cease until the U.K. has left the EU and can negotiate its future trading relationship with the bloc as a non-member state.

A senior No. 10 official said the British government is "either going to be negotiating a new deal or working on no deal — nobody will work on delay [to Brexit]."

"We will keep fighting to respect the biggest democratic vote in British history. The EU is obliged by EU law only to negotiate with member state governments, they cannot negotiate with parliament, and this government will not negotiate delay," the official said.

Addressing the party conference on Wednesday afternoon, Johnson is expected to reiterate his call for a speedy conclusion to the Brexit deadlock.

"Voters are desperate for us to focus on their other priorities — what people want, what Leavers want, what Remainers want, what the whole world wants, is to move on," he is expected to say, according to lines from the speech shared with journalists by the party.

On Tuesday, Johnson acknowledged that the U.K. would have to include customs checks on the island of Ireland once it has left the bloc.

"That is why we are coming out of the EU on October 31. Let’s get Brexit done — we can, we must and we will."

On Tuesday, Johnson acknowledged that the U.K. would have to include customs checks on the island of Ireland once it has left the bloc — something that Theresa May's government opposed. However, he denied reports that these checks would take place at checkpoints only a few miles from the border.

The U.K. plan is also expected to include provisions for Northern Ireland to continue to abide by EU laws governing agricultural trade, to ensure the continuance of the "all-island" cross-border economy in this area.

The backstop contained in May's Withdrawal Agreement, an insurance mechanism for avoiding a hard border on the island of Ireland — which if triggered would see the U.K. as a whole remain in a customs union with the EU — was a key target for domestic opposition to her deal, which was rejected three times by the U.K. parliament earlier this year.