LONDON (BLOOMBERG) - British Prime Minister Theresa May will call on opposition lawmakers to help steer Britain out of the European Union as she seeks to reset after her standing was diminished by last month's disastrous general election.

Mrs May, who is now reliant on the votes of Northern Ireland's Democratic Unionists to get her agenda through Parliament, will restate her political mission to tackle "injustice and vested interests that threaten to hold us back".

Social and economic reform is needed to make a success of Brexit, she will say in a speech on Tuesday, but in a sign of her weakness, will call for cross-party cooperation to deliver it.

"I say to the other parties in the House of Commons, come forward with your own views and ideas about how we can tackle these challenges as a country," Mrs May will say, according to extracts of the speech released by her office. "We can play it safe or we can strike out with renewed courage and vigour, making the case for our ideas and values and challenging our opponents to contribute, not just criticise."

Mrs May came under fire from her own party over the weekend as she prepared to publish a draft law this week intended to repeal Britain's membership in the EU, and set a new legal framework for the country after it withdraws from the bloc.

Some of her Conservative Party colleagues have talked openly of the need to replace her, while opposition lawmakers are preparing a series of challenges to her parliamentary authority.

Mrs May, who took office on July 13, 2016, insists she will still be prime minister in 2018, despite losing her majority. She received a boost on Saturday when US President Donald Trump said a trade deal with Britain will be done "very, very quickly".

But even that met with mixed reaction, with the Confederation of British Industry (CBI) urging the government to tread cautiously in its dealings with the US. Trade deals are complex "and we don't want to walk into a bear hug", CBI president Paul Drechsler told Sky's "Sophy Ridge on Sunday" show.

Mrs May's weakened position, having lost her majority and now trailing the opposition Labour Party in opinion polls, has reopened the debate over how Brexit should unfold, with some of her own most senior ministers now emboldened to disagree with her.

Chancellor of the Exchequer Philip Hammond last week called for a Brexit deal that keeps Britain close to the EU market, warning "it would be madness" to reject trade ties. In Brussels, the EU's Brexit negotiator Michel Barnier sent the message that Mrs May should forget her dream of a "frictionless" trade deal, and that the road to divorce will be hard.

Mrs May, who called the June 8 election with the expectation of tightening her grip on the House of Commons and strengthening her hand in Brexit talks, will acknowledge her loss of authority in Parliament in her speech but pledge to fight on as she seeks to put the election result behind her.

"I led a majority government in the House of Commons. The reality I now face as prime minister is rather different," she will say. "In this new context, it will be even more important to make the case for our policies and our values, and to win the battle of ideas both in Parliament as well as in the country."

Opposition parties are preparing to join forces with rebel lawmakers in Mrs May's own Conservative Party to hamper the progress of the government's Repeal Bill, which is due to be published this week. It would reverse the European Communities Act of 1972, which gave effect to EU law in the UK, and graft EU statutes into British law, giving ministers sweeping powers to adapt legislation without parliamentary scrutiny.

Mr Keir Starmer, Brexit spokesman for the opposition Labour Party, told the BBC it is "highly likely" he will seek to amend the Bill to limit the role of the executive in changing laws and increase the power of Parliament. His party leader Jeremy Corbyn has also pledged to preserve EU environmental and employment protections.

In evidence of cross-party cooperation, former Conservative minister Ed Vaizey co-wrote an article for the Sunday Telegraph newspaper with Labour's Rachel Reeves, saying Britain should remain in Euratom, the bloc's nuclear watchdog. Mrs May says she wants to quit the regulatory body because it is subject to rulings by the European Court of Justice.

Justice Secretary David Lidington said the government is focusing on the "real problems" and should not be distracted by speculation over Mrs May's leadership. That followed a report in the Mail On Sunday newspaper that said former Cabinet minister Andrew Mitchell had said during a private dinner that Mrs May should resign.

"Too much sun, too much warm Prosecco, led to gossipy stories in the media," Mr Lidington said in an interview on BBC Television's Andrew Marr Show. Voters want politicians to "go away and deal with the real problems people in this country are facing".

Mr Mitchell, a close ally of Brexit Secretary David Davis, told Conservative Members of Parliament at a June 26 dinner that the party needs a new leader, the Mail said, citing a lawmaker at the gathering.

Mr Mitchell downplayed the Mail's story, describing it in a statement to Bloomberg as "an overheated report of a private dinner conversation".