LONDON, July 22 (Xinhua) -- Votes counting started Monday night in a ballot to decide who will become the next prime minister of Britain.

Voting among 160,000 Conservative Party members closed at 5 p.m. local time, just hours after Foreign Office Minister Sir Alan Duncan resigned his government job in protest against Boris Johnson likely to be the person to enter 10 Downing Street.

Other senior ministers, including Chancellor of the Exchequer Philip Hammond and Justice Secretary David Gauke have both said publicly they would resign if Johnson is declared the winner on Tuesday.

Party officials will count the votes from around the country during the night before the results expected on Tuesday.

Wednesday is already lined up as an historic day in British politics, with Theresa May making her last ever appearance at Prime Minister's Question Time in the House of Commons. She is also expected to make a farewell speech.

Early Wednesday afternoon May will travel to Buckingham Palace to offer her resignation as prime minister to Queen Elizabeth. An hour later the winner of the leadership contest will also travel to the palace to be appointed as prime minister by the British monarch.

The winner will then head to 10 Downing Street where a speech will be made in front of one of the world's most famous front doors at around 5 p.m.

The Daily Telegraph reported Monday that should Johnson win, his girlfriend Carrie Symonds will not join him for his big moment entering Downing Street as prime minister. The Telegraph said Johnson will enter his new home alone as Symonds does not want to become a distraction "on the most important day of his life".

During early Wednesday evening the new prime minister is expected to start the task of assembling a new cabinet, with the great offices of state, foreign secretary, home secretary and defense secretary all likely to be among the first to be appointed.

The handing out of jobs, ranging from secretaries of state to junior ministers is expected to take several days before the full team is finalized.

Political commentators say one of the problems for Johnson to navigate, if he wins the contest, will be the arrival of heavyweights such as Hammond, Gauke and Duncan on the back benches in the House of Commons. There, they will no longer be shackled by the assumed rules of collective responsibility, expected of government ministers.

Further down the line, he has vowed to bring Britain out of the European Union on Oct. 31, with or without a deal with Brussels.

Pro-Europe Conservatives are already threatening to block a no-deal departure.