Theresa May has urged parliament to “get it done” and back her Brexit deal, in an impassioned speech that offered no new concessions for wavering MPs before next week’s crucial vote.

Speaking at a dockside warehouse in the pro-leave town of Grimsby, May repeatedly declined to accept any personal responsibility for the ongoing uncertainty or give any clues as to what she would do if the vote was lost.

The speech prompted a withering response from the CBI, whose deputy head said the prime minister’s message was “not good enough”.

Addressing workers from Ørsted, a Danish energy and wind turbine firm, May urged the EU to make new concessions over the Irish backstop – the issue that caused many of her MPs to vote against the deal the first time – before expected last-ditch talks in Brussels this weekend.

May accused Jeremy Corbyn of trying to frustrate Brexit, and she implored Labour MPs in leave-voting seats, such as Grimsby’s Melanie Onn who attended the event, to back her deal.

She said if her plan was voted down again in the Commons on Tuesday, the result would be more economic uncertainty and delay and the possibility of Brexit being either watered down or even overturned.

A vote against the deal would mean “not completing Brexit and getting on with all the other important issues people care about, just yet more months and years arguing”, May said. “If we go down that road we might never leave the EU at all.”

She added: “My message to those MPs who agree with me that we should not risk that is simple: the only certain way to avoid it is to back the deal the government has secured with EU on Tuesday. Let’s get it done.”

The EU “has to make a choice too”, the prime minister said. “We are both participants in this process. It is in the European interest for the UK to leave with a deal. We are working with them but the decisions that the European Union makes over the next few days will have a big impact on the outcome of the vote.

“European leaders tell me they worry that time is running out and that we only have one chance to get it right. My message to them is: now is the moment for us to act.”

May again talked up her plans on workers’ rights and the redevelopment of towns such as Grimsby, stressing what she said were the benefits of her deal to the fishing industry. However, there was nothing new in policy terms.

Asked three times after the speech if she accepted any personal blame, May refused to engage with the issue or say what might happen if the deal was lost again.

Asked if she was to blame at all for the lack of certainty just three weeks before the supposed departure date of 29 March, May said: “You mentioned the next few weeks – I would say now is the moment for us to get this done. Now is the moment for parliament to back the deal and to deliver what people voted for.”

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Asked what might happen with promised votes on no deal or extending the Brexit deadline if her vote was lost, May said: “My focus is on the debate that will take place on Tuesday and getting that vote through.”

Asked whether she owed business an apology rather than an explanation for what could happen after Tuesday, May said it was up to MPs to “vote to end that uncertainty”.

Joshua Hardie, the deputy director general of the CBI, tweeted: “Businesses are tired of Groundhog Day. If the government deal falls, MPs must avoid no deal and get behind something else, fast. Meanwhile investment and sales will continue to suffer.”

A Labour source said of May’s speech: “Is that it? What a waste of everyone’s time. There was nothing new, just more time-wasting and running down the clock. She really is in trouble.”

Adding to the sense of disquiet, as May left the venue she faced a shouted question from ITV’s correspondent Libby Wiener as to why, on International Women’s Day, only one female journalist had been selected for a question, and four men. May replied: “You’ve had answers from a woman prime minister.”