Story highlights UK's Foreign Secretary met Steve Bannon and Jared Kushner yesterday

Boris Johnson is the UK's highest profile pro-Brexit politician

(CNN) UK Foreign Secretary Boris Johnson is to meet key Congressional leaders in Washington today including Speaker of the House Paul Ryan, Senator Bob Corker and Senator Mitch McConnell, the UK Foreign Office said in a statement.

Johnson arrived in New York on Sunday where he held meetings with Steve Bannon, Trump's chief strategist, and Jared Kushner, the President-elect's son-in-law and close adviser during the transition, a UK Foreign Office official confirmed.

He will not meet with Rex Tillerson -- the nominee for US Secretary of State -- as the protocol is to wait until after the confirmation process, which is due to begin later this week.

Johnson, a former mayor of London, was given his current position following the narrow success of 2016's referendum to leave the European Union, commonly referred to as Brexit. A former journalist and television personality, he was the highest profile supporter of the "Leave" campaign.

He is the UK's first Foreign Secretary to also be an American citizen. He was born in New York, and holds dual citizenship.