Donald Trump said he will unveil a “full and comprehensive” trade deal with the United Kingdom Thursday.

The U.S. president teased the announcement in a Wednesday night post on Truth Social, promising a “Big News Conference” at 10 a.m. EDT.

In a follow-up post Thursday morning, he said: “The agreement with the United Kingdom is a full and comprehensive one that will cement the relationship between the United States and the United Kingdom for many years to come.

“Because of our long time history and allegiance together, it is a great honor to have the United Kingdom as our FIRST announcement. Many other deals, which are in serious stages of negotiation, to follow!”

Specifics of the agreement were not immediately available. But the pact would represent a significant step forward for the United States, which has been mired in negotiations with dozens of countries since slapping hefty tariffs on its global trading partners last month.

It would also represent a win for U.K. Prime Minister Keir Starmer, who is struggling in the polls and has tried to prioritize building bridges with Washington at a time other world leaders have taken a confrontational approach.

A spokesperson for Starmer said Thursday morning: “The Prime Minister will always act in Britain’s national interest — for workers, for business, for families.

“The United States is an indispensable ally for both our economic and national security. Talks on a deal between our countries have been continuing at pace and the Prime Minister will update later today.”

Starmer and his ministers want the deal to lower the White House’s 25 percent tariffs on imports from Britain’s automotive, steel and aluminum sectors and guard against further tariff rises on pharmaceutical exports.

The deal is the first to be announced during the 90-day pause on Trump’s “Liberation Day” tariffs announced last month.