May will tell her Conservative Party on Wednesday that the impending divorce from the European Union is an opportunity that opens up a future full of promise, assuring the faithful: "We have everything we need to succeed."

"It could be a potentially big day for the sterling... it is going to be interesting to see what impact the PM's speech has on the currency as the day goes on," said Connor Campbell, a financial analyst at Spreadex.

Sterling has been hit hard by concerns over a growing conflict over May's Brexit plan with the pound falling to a Sept. 10 low of $1.2979 in the previous session.

May's speech will be watched keenly by investors for clues on whether she can persuade senior members of the ruling Conservative Party to accept her so-called Chequers plan to leave the EU.

On Wednesday, the pound was broadly flat at $1.2996 and steadied against the euro at 89.06 pence.

Manufacturing PMI data due shortly will likely show the services sector increasing to 54 compared to 54.3 in September, according to a Reuters poll.