The head of one of Northern Ireland's largest business banks has warned a no-deal Brexit would cause an "existential" challenge for companies.
The region is already dealing with limited economic growth, and the largest trade delegation from Belfast ever to visit Westminster has published a 10-year plan it says will create 65,000 jobs.
The alliance of retailers, the hospitality industry and manufacturers expressed concern at uncertainty surrounding Brexit and the prospect of no-deal.
Kevin Kingston, chief executive officer of Danske Bank UK, said: "When you move down to the smaller businesses it becomes much more difficult, some of them are facing an existential challenge and it is very hard to plan for outcomes when it is that fundamental to your business model.
"For the smaller businesses, I don't think they are ready (for no deal) but I am not saying that as a criticism, I am saying that is a cold, hard reality of the challenges they face.
"Everybody needs to do more.
"This is an opportunity and a time when Northern Ireland needs to stand together and work together to find solutions to whatever the outcomes may be in terms of the Brexit negotiations."
Danske lends to more than one in three of Northern Ireland businesses.
Mr Kingston said the business community was seeking realistic solutions.
He said: "My sense is that reality is growing and the desire to bring forward the solution which addresses the challenges of Northern Ireland.
"That needs to happen very quickly, all my customers are saying they need that certainty, they need that guidance so that they can move forward and plan, I hope it does."
The 10-year plan created by Trade NI aims to break the "cycle of limited economic growth" in the region.
The new alliance was formed by trade representative bodies Hospitality Ulster, Manufacturing NI and Retail NI.
The group said its economic plan will set out policy priorities with the potential to create 65,000 jobs and make Northern Ireland a high-growth economy.
It expressed concern at the uncertainty around Brexit and the collapse of the Northern Ireland Assembly, and stressed that any new executive must increase the productivity of the workforce, reduce the regulatory burden on businesses, increase skills, and deliver a clear economic strategy.
North Belfast DUP MP Nigel Dodds said Brexit was a challenge, but there were many fundamentally good things about the Northern Ireland economy.
"We don't minimise any of the challenges that are out there but collectively I think Northern Ireland has come through an awful lot and has got to the place it is and we need to work our way through that because everybody wants to move forward and everybody wants to get a deal so we need to try and move forward together."
Northern Ireland Secretary Julian Smith said the Prime Minister was working "flat out" to strike a deal on Brexit.
He said: "I think there are lots of options on how we resolve this issue and I have no doubt that the Prime Minister and his team are working at pace and I am providing as much input as I can from the Northern Ireland/Ireland perspective that I am getting."
Glyn Roberts, who leads smaller traders' body Retail NI, said Northern Ireland was "open for business" and warned a no-deal Brexit was not an option.
He said Northern Ireland should be a gateway to the EU and a globally-facing region as well as an "eco-system" for innovation, with local political leaders making bold decisions.
"Real leaders do not see problems, they see solutions."
Colin Neill from Hospitality Ulster said Northern Ireland needed to reduce its reliance on imported goods and said firms were "stifled" by high energy costs and rates bills.
Stephen Kelly, from Manufacturing NI, said a restored ministerial Executive after almost three years in suspension was needed at Stormont to take critical decisions.
"Northern Ireland punches well above our weight, but we cannot fight with one hand behind our back."
He added: "We need to set the Northern Ireland business community free."