Theresa May has spoken to the leaders of two of the biggest unions in the UK as she continues to try to build support for her Brexit deal. The PM spoke to Unite's Len McCluskey and the GMB's Tim Roache by phone on Thursday in what her spokesman described as "constructive" calls. He said Mrs May was undertaking "widespread engagement" about the deal. Mr Roache said he was glad the PM had "finally picked up the phone" but that her deal was not "good enough". "If the deal genuinely did the job for GMB members, our union would support it, but it doesn't," he said. "It's clear more time is required, we need to extend Article 50 and ultimately give the final say on Brexit to the public." Follow updates from the House of Commons liveBrexit: A really simple guideCorbyn calls for election over BrexitWorld against no-deal Brexit - Japan PMMrs May also spoke to John Allan, president of the CBI business lobby group, as MPs continue to debate the EU withdrawal agreement her government has negotiated with the EU, ahead of next Tuesday's vote. She has also met some Labour MPs as she continues efforts to build support for the deal, which more than 100 of her own MPs have said they will oppose. Asked if she was still ruling out Labour's policy of a permanent customs union with the EU, after talking to the party's MPs and union leaders, she her deal would deliver an "ambitious" trading arrangements with the EU and allow the UK to strike trade deals around the world. At a press conference with Japanese prime minister Shinzo Abe on Thursday, she said her deal was in the national interest "because it's a good deal and therefore I hope that it will get widespread support across the whole of Parliament". Speaking alongside Mrs May in Downing Street, Mr Abe said his country was in "total support" of Mrs May's EU withdrawal agreement and wanted to "invest more into your country and to enjoy further economic growth with the UK". "That is why we truly hope that a no-deal Brexit will be avoided, and in fact that is the whole wish of the whole world," he added. It has emerged that the government is considering backing an amendment from Labour Leave supporter John Mann, giving extra protections to workers and the environment, in a bid to win support. A number of Labour MPs in Leave-supporting constituencies back Mr Mann's amendment, which the MP said would open up the opportunity for other improvements to the prime minister's deal. A spokesman for the prime minister said it was something they would "consider very seriously", adding that the government had "a long standing commitment to strong labour protections". Mr Mann told BBC News his amendment would make it more likely for him to back the deal, but admitted it didn't mean other Labour MPs would be "rushing" to do the same. But Labour Leader Jeremy Corbyn said his party did not "accept or endorse" what was on offer in the proposed amendment. He said it has already been "quite clearly and emphatically rejected" by leading trade unions. AFP.