U.K. International Trade Secretary Liz Truss will meet with her U.S. counterpart Robert Lighthizer in Washington on Monday as part of the third round of talks to reach a trade deal between the two countries.

Prime Minister Boris Johnson put an agreement with the U.S. at the heart of his plans for the U.K. economy after Brexit, and Truss’s decision to travel during the coronavirus pandemic reflects London’s commitment to a deal.

“The Secretary of State is meeting Robert Lighthizer during a critical time in the negotiations and it is essential we agree the next steps and priorities for the trade talks,” the Department for International Trade said in a statement. “A deal will be a key driver in leveling up the U.K. by boosting the economy by 15 billion pounds ($19.6 billion) and removing almost half a billion pounds worth of tariffs.”

The talks have been beset by disagreements, over agriculture in particular, and Lighthizer has said an agreement is “unlikely” this year, meaning Britain is set to complete its departure from the European Union on Dec. 31 without a trans-Atlantic trade deal in place.

Truss will also use the talks to press for the removal of retaliatory tariffs imposed as part of the dispute over subsidies for Boeing Co. and Airbus SE.

“We will be tough in pressing our interests. The U.S. talk a good game about free trade and low tariffs, but the reality is that many U.K. products are being kept unfairly out of their market,” Truss told lawmakers in June. “Tit-for-tat tariffs” are “harming businesses on both sides of the Atlantic and I don’t want to see any more.”