Brexit debate: Which MPs oppose Theresa May's agreement and why have so many spoken out against it?

Theresa May will plead for MPs to back her Brexit deal as she speaks during a marathon five-day debate in Parliament over the plans.

Ahead of a vote on the agreement on December 11, the Prime Minister will stress the need to respect the 2016 referendum result and urge that backing her deal will reunite a divided nation.

But she faces widespread opposition across the Commons – including both Leave and Remain wings of her own party.

Ahead of the crunch vote, here we outline which MPs oppose Mrs May's agreement and why.

Brexiteers

Brexiteers claim the deal risks leaving the UK a 'vassal state' bound by Brussels' rules without any say over them

Their concerns mainly focus on the backstop measures aimed at preventing a hard border with Ireland, under which the UK would be in a "single customs territory" with the EU, while Northern Ireland would remain aligned with many Single Market rules.

Prominent Eurosceptic Jacob Rees-Mogg said "in some areas it will leave the United Kingdom with even less control than it currently has: the vassal state".

Boris Johnson

Former foreign secretary Boris Johnson said the UK would be a "satellite state" of Brussels.

In his resignation letter, former Brexit secretary Dominic Raab said "no democratic nation has ever signed up to be bound by such an extensive regime, imposed externally without any democratic control over the laws to be applied, nor the ability to decide to exit the arrangement".

There are also concerns about the extent to which the UK will seek to remain aligned with the EU under the terms of any deal aimed at avoiding the need for the backstop - many Brexiteers would prefer a looser, Canada-style free trade agreement.

DUP

The DUP's 'blood red' line on avoiding a border down the Irish Sea

The 10 DUP MPs prop up Mrs May's administration in the Commons but that support appears to have collapsed over the Brexit deal.

They will not accept any measure which effectively creates a trade barrier down the Irish Sea between Great Britain and Northern Ireland - something they believe the backstop does.

DUP leader Arlene Foster told her party's conference in November that "as things stand we would be sowing the seeds of inevitable economic divergence from our largest market" in the rest of the UK.

The Labour Party

Labour says the deal fails to meet its tests for a 'jobs-first Brexit'

Jeremy Corbyn said any deal would have to include "a permanent customs union" with the UK having a say over future trade agreements, a "strong single market deal" and "guarantees on workers' rights, consumer and environmental protections".

- The Opposition also sees the vote as a way to oust Mrs May and install Mr Corbyn in Downing Street.

Labour's official policy is to call for a General Election if Mrs May fails to get her Brexit plan through Parliament.

It is "inevitable" the Opposition would move a motion of no confidence in Mrs May's government if she loses the vote, shadow Brexit secretary Sir Keir Starmer has said.

Pro-EU MPs hoping for second referendum

Some MPs hope by rejecting Mrs May's deal, they can push for the final decision on Brexit being handed back to the public.

Former transport minister Jo Johnson quit the government in November as the finishing touches were being put to the deal and said the public should be asked to vote again in order to avoid the choice between "vassalage" of the deal and the "chaos" of a no-deal Brexit.

Additional reporting by PA.