The divisions within Britain's governing Conservative Party -- one of the biggest obstacles to a Brexit deal and a central reason for the 2016 referendum being called -- are being laid bare as it holds its annual conference in Birmingham this week.

With former foreign secretary Boris Johnson set to make a high profile speech on Tuesday and Prime Minister Theresa May to give the keynote address on Wednesday, CGTN Digital lays out the main camps, some key players and their motivations.

Chequers

Theresa May - Prime minister

May continues to insist her Chequers plan is the only viable option for leaving the EU without re-imposing a hard border between northern and southern Ireland. Her plan is a series of compromises that no one really likes -- it has been rejected by many of her own MPs, the opposition, and the EU -- but is being sold as the least worst option.  

Supporters: May has calculated support for her plan from those wanting to keep the party together -- principally government ministers. There is no clear alternative to her as prime minister, and many Conservative MPs are terrified that voting down her Brexit plan or triggering a leadership contest would lead to a general election they would lose.

Free traders

Boris Johnson - Former foreign secretary

Johnson, who resigned as foreign secretary over the Chequers plan, wants a free trade deal similar to that which Canada and the EU have agreed to. Speculation persists that he intends to challenge May for the party leadership, and on Sunday he used a newspaper article to put forward domestic policy ideas as well as criticize the Chequers plan.

Supporters: The colorful Johnson has lost some of his support with members and has never been particularly popular with colleagues, but is broadly representative of a group which sees Brexit as a chance for Britain to be more internationalist and outward looking.

Old guard

Jacob Rees-Mogg - Backbench MP

Rees-Mogg has been ridiculed as an outdated throwback, but his unique style has led a strong media profile and he has emerged as the leader of a group of hard-right Conservatives opposed to the Chequers plan and demanding a clean break from the EU.  

Supporters: Rees-Mogg is popular with turn-the-clock-back Conservatives and has a cult following among some young party supporters. The pro-Brexit European Research Group which he leads includes around 60 MPs -- easily enough to stop the Chequers plan passing through parliament.   

Second referendum

Justine Greening - Former education secretary

A group of influential Conservatives remain opposed to leaving the EU, and at best want the softest of soft Brexits. Some, including Greening, have now called for a second referendum to be held. The former education secretary has also launched criticisms of May's leadership, and is seen as a possible challenger.  

Supporters: The moderate internationalists who dominated the party under the leadership of David Cameron and George Osborne fall broadly in line with this group, which includes a number of former senior ministers and former prime minister Sir John Major. 

Whatever works

Michael Gove - Environment secretary

Gove campaigned for Brexit, breaking his long friendship with then prime minister David Cameron in the process. He is seen as practical and willing to compromise, and has backed May's plan with the asterisk that it is open to change. "I'm in favor of a 'super Britain' deal," he said at the beginning of the party conference.

Supporters: Gove has credentials as a reformist, serious politician and his support bridges party divides. However, he burnt some bridges by leading Johnson's leadership bid in 2016 before abandoning him in an ill-fated attempt to take the top job for himself.