Outside the conference centre, hundreds of people held signs both backing and opposing Brexit
Birmingham (United Kingdom) (AFP) - British Prime Minister Theresa May and her allies called for unity Sunday after former colleague Boris Johnson hijacked the opening of their Conservative party's annual conference with another attack on the government's Brexit plan.
Former foreign minister Johnson, long tipped as a successor to May, used a newspaper interview to condemn her plan for close economic ties with the EU as "deranged" and "preposterous".
He is among a group of eurosceptics in her Conservative party who are using the four-day gathering in Birmingham, central England, to make the case for a looser trade agreement.
Several backbench MPs also joined former UK Independence Party (UKIP) leader Nigel Farage, a leading Brexit campaigner, at a rally here Sunday, demanding May "chuck" her plan.
The prime minister is already under intense pressure from EU leaders, who earlier this month rejected her trade plan and demanded a rethink before a summit in mid-October.
Meanwhile pro-European Conservatives joined hundreds of people chanting "Bollocks to Brexit" at a rival rally calling for a new EU referendum.
May has repeated ruled out a new Brexit vote, and insists her plan is the only way to protect cross-border trade in goods and avoid physical checks on the Irish border.
"My message to my party is, let's come together and get the best deal for Britain," she told the BBC in an interview.
Analysts believe May will have to give further ground to Brussels to secure a withdrawal agreement before Brexit in March next year, but no announcements are expected in Birmingham.
Johnson's successor, Foreign Secretary Jeremy Hunt, warned EU leaders not to make the bloc a prison, or "we won't be the only prisoner that will want to escape".
But his conference speech also had a message for colleagues that their in-fighting threatened undermining Brexit, or handing power to opposition leftist leader Jeremy Corbyn.
"Never forget that disunity and division won’t give us a better Brexit but the wrong Brexit, a Corbyn Brexit or perhaps no Brexit at all," he said.
- Threats to leadership -
Since losing her parliamentary majority in a disastrous snap election last year, May has faced endless internal plotting and rumours of a leadership challenge.
Many potential successors inside and outside her cabinet will address delegates this week, notably Johnson, who quit in July over May's Brexit plan.
Charismatic and with a populist touch, Johnson is a favourite with the Conservative faithful and is expected to draw large crowds to his speech at a fringe event on Tuesday.
In his interview with the Sunday Times, he made a direct pitch for the leadership by setting out a slew of domestic policy ideas.
But many believe May's rivals will wait and see what happens in the EU talks, with the House of Commons due to vote on the final Brexit deal, possibly in November or December.
May only has a slim working majority among the 650 MPs, making her vulnerable to even the smallest rebellion.
Few delegates here want an immediate change of leader, even those unhappy with May's plan. "I think it's got to wait until after Brexit," said Alan Dixon, 72, from Derby.
- Labour threat -
The opening to the conference was overshadowed by a security breach in the mobile app for the event which allowed users to access phone numbers of senior ministers and MPs.
It was an inauspicious start to a meeting that many Conservatives were already anxious about.
They want the party to present something more than Brexit divisions, as they eye the threat posed by the opposition Labour party.
Corbyn presented a radical economic programme for government at his own conference last week.
The party also said it would likely reject May's Brexit deal when it comes to a vote of MPs, raising the possibility of fresh elections.
The Conservatives are slightly ahead of Labour in opinion polls, but a slew of senior figures have warned they need new ideas.
May announced plans on Sunday to increase the property purchase tax for foreign buyers amid concerns overseas investors are driving up prices, and a national festival in 2022 to show off post-Brexit Britain.