By Michael Holden and Elizabeth Piper
LONDON (Reuters) - British Prime Minister Theresa May's Conservative Party began gathering for its annual conference on Saturday with bitter divisions over her Brexit plans rising to the fore, raising doubts about her own future.
Britain is due to leave the European Union on March 29, 2019, but the terms of the departure remain unclear. May, under fire from critics in Brussels, opponents at home and some lawmakers in her own party, has said talks on a divorce deal are at an impasse.
In an interview with the Sunday Times newspaper ahead of her party's conference, May took aim at those who have scorned her "Chequers" Brexit proposals accusing them of "playing politics" with Britain’s future and undermining the national interest.
However, in a demonstration of the challenge she faces, the newspaper ran an interview with former foreign minister Boris Johnson alongside on its front page in which he openly questioned May's commitment to Brexit and called her plans "deranged."
"Unlike the prime minister I campaigned for Brexit,” said Johnson, the bookmakers' favourite to succeed May who on Friday declined to answer directly whether he would rule out a leadership challenge.
"Unlike the prime minister I fought for this, I believe in it, I think it’s the right thing for our country and I think that what is happening now is, alas, not what people were promised in 2016."
May says her "Chequers" proposals are the only viable option, but EU leaders have said parts of them are unacceptable and many Conservative lawmakers have threatened to vote down a deal based on May's blueprint.
The uncertainty has led to business concerns that there will be no deal, potentially leading to tariffs and border delays.
Japanese carmaker Toyota on Saturday warned that leaving without an agreement would hit its production and jobs would ultimately be at risk.
"Of course we want a deal," Business Secretary Greg Clark, one of those who supports May's plans which seeks free trade of goods with the EU, told BBC radio.
"We need to have a deal. The evidence from not just Toyota and other manufacturers is we need absolutely to be able to continue what has been a highly successful set of supply chains."
A summit of EU leaders last week ended in a blunt dismissal of May's proposals, which they said would fail to resolve arguments over the land border of Northern Ireland, in the UK, with the Irish Republic, in the EU, one of the main sticking points to a deal.