Theresa May tries to rally Conservatives, but warns no-deal Brexit would be tough for Britain

British Prime Minister Theresa May calls on her Conservative Party to pull together and unite behind her plan to leave the European Union, saying "if we hold our nerve" she can win a deal "that delivers for Britain."

Conservatives have been bitterly divided over her Chequers plan with months to go before EU divorce

British Prime Minister Theresa May delivers her leader's speech during the final day of the Conservative Party Conference at the International Convention Centre in Birmingham on Wednesday. (Christopher Furlong/Getty Images)

British Prime Minister Theresa May called on her Conservative Party on Wednesday to pull together and unite behind her plan to leave the European Union, saying "if we hold our nerve" she can win a deal "that delivers for Britain."

May is urging her fractious Conservative Party to unite and help her seal a deal with the bloc.

With Britain set to leave the bloc on March 29, talks are stalled and a powerful pro-Brexit faction in May's party is urging her to be tough and, if need be, walk away without a deal.

In a speech to the party's annual conference in Birmingham on Wednesday, she said "leaving without a deal — introducing tariffs and costly checks at the border — would be a bad outcome for the U.K. and the EU," though she refused to rule it out.

She said it would be tough at first, but Britain's "resilience and ingenuity" would see it through. She reiterated that the voters have spoken and there would be no second referendum.

"What we are proposing is very challenging for the EU," she said. "But if we stick together and hold our nerve I know we can get a deal that delivers for Britain."

Jabs at Labour, Johnson

Her plea to unify behind "decent, moderate and patriotic" policies came a day after her rival and former foreign secretary Boris Johnson trashed her so-called Chequers plan for Brexit and challenged her authority, though he stopped short of declaring his intentions to be the next party leader.

"It is no surprise that we have had a range of different views expressed this week," she said. "But my job as prime minister is to do what I believe to be in the national interest. And that means two things. First, honouring the result of the referendum ... and secondly, to seek a good trading and security relationship with our neighbours after we have left."

The referendum was called by May's predecessor, David Cameron. After winning the party leadership battle in 2016, she sought to solidify her claim with a spring 2017 election, but the Conservatives lost 13 seats and needed the pledge of Northern Ireland's Democratic Unionist Party and their 10 seats to remain in power.

DUP Leader Arlene Foster has used the conference to loudly set out her red lines for Brexit, repeating that she will not accept a border between Northern Ireland and the rest of the United Kingdom. "The red line is blood red," she told the BBC.

British Prime Minister Theresa May salutes the gathering in Birmingham with her husband Philip after an ovation following her speech. (Darren Staples/Reuters)

May also tried to expand her domestic agenda in her speech, attacking the main opposition Labour Party by saying their policies, including the renationalization of mail, rail and utilities, would mean increased taxes and drive away business.

Labour Leader Jeremy Corbyn, she said, would "outsource our conscience to the Kremlin."

Labour has given every indication it will vote against whatever deal May can negotiate with the EU.

May received a standing ovation after dancing onto the stage to Dancing Queen by ABBA, a self-deprecating reference to social media memes that emerged after she danced at a ceremony on her recent trip to Africa.

She was not plagued by the mishaps of last year's speech, which was dogged by a bad cough and falling signage onstage.

With files from CBC News and The Associated Press