(Bloomberg) -- Foreign Secretary Liz Truss will handle the U.K.’s post-Brexit negotiations with the European Union after David Frost quit the role, adding even more powers to her brief and strengthening her position as one of the favorites to succeed Boris Johnson as prime minister.

The appointment of one of the most popular Conservatives among the grassroots was announced in a statement on Saturday by Johnson’s office less than 24 hours after the shock resignation of Frost. 

The move consolidates Truss’s status as a potential future Tory leader, especially as Johnson’s star has plummeted. After Johnson, she is arguably the most powerful person in government next to Chancellor of the Exchequer Rishi Sunak, another name touted as future prime minister material.

Johnson’s quick move to fill the post with a cabinet big-hitter underlines the importance he places on the role as the U.K. tries to reshape trading terms it agreed just a year ago with the bloc. Truss campaigned for Remain in the 2016 referendum, but has since embraced Brexit with the zeal of a convert. 

She now has the power, and Johnson’s ear, to shape the U.K.’s relationship with its closest neighbors aftera fractious divorce from the EU. If Brussels was hoping for a soft touch, Truss would not be it. An ardent fan of Margaret Thatcher, both in her embrace of free markets and her disdain for the EU, she operates within a party that has largely purged a lot of it europhiles.

At the top of Truss’s inbox in her new role will be to see through negotiations opened by Frost with the EU to unpick trading arrangements between Northern Ireland and mainland Great Britain. 

Under the so-called Northern Ireland Protocol, goods moving into the region from the rest of the U.K. are subject to customs checks if they may later be moved into the EU. Britain is demanding changes to the accord, which the government says has inhibited trade between different parts of the U.K.’s own single market.

The foreign secretary was promoted from the international trade portfolio to her current role in September, and is credited by party members with reaching a succession of rollover trade deals during her tenure in her old post.

Even after moving, she’s said she sees trade as an extension of her new role in the Foreign Office and has overshadowed her successor in the trade department.

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