The EU will seek to sweeten its package of proposals over the post-Brexit arrangements for Northern Ireland by lifting a prohibition on sausages made in Britain.

The EU’s Brexit commissioner, Maroš Šefčovič, will table four papers on Wednesday as to how the Northern Ireland protocol can be improved.

The substantial package will cover a range of problems, including the availability of medicines approved in the rest of the UK, inspections on meat, dairy and plant products, and customs facilitation.

Included will be a proposed “national identity” exemption for British sausages from the EU’s prohibition on prepared meat from a third country, sources said.

Northern Ireland’s institutions will also be given a stronger voice in Brussels in order to deal with the democratic deficit caused by the region staying within the single market but without a say on legislation.

The issue of sausages and other prepared meats has become a talismanic issue for Boris Johnson, who had said he would do “whatever it takes” to ensure people in Northern Ireland retained access.

It has been leveraged by ministers to highlight the imbalance in the protocol, which the UK government says is distorting trade and undermining the unionist communities’ sense of identity.

During a joint press conference with the German chancellor, Angela Merkel, in July, Johnson had told reporters: “Imagine if bratwurst could not be moved from Dortmund to Düsseldorf because of the jurisdiction of an international court – you’d think it was absolutely extraordinary.”

The prime minister and his Brexit minister, David Frost, have repeatedly threatened to trigger article 16 suspending parts of the protocol unless there is a thoroughgoing renegotiation.

Joe Biden’s national security adviser, Jake Sullivan, gave the prime minister a boost in his demand for a full renegotiation on Thursday evening. While telling the BBC that the US president was concerned about a risk to the stability posed by a potential failure of the British government and Brussels to find a compromise in the coming weeks, he fell short of supporting the EU stance that the protocol should not undergo a major renegotiation.

“The Northern Ireland protocol was agreed between the EU and the UK and our view is that the two sides should work together in a constructive way to find a deal and a way forward,” he told the BBC.

“Without something like the Northern Ireland protocol and with the possibility of the return of a hard border between NI and the Republic of Ireland, we will have a serious risk to stability and to the sanctity of the Good Friday agreement, and that is of significant concern to the US.”

The EU has said it will not renegotiate the fundamentals of the protocol, which in effect keeps Northern Ireland in the bloc’s single market and draws a customs border down the Irish Sea so as to avoid a hard border on the island of Ireland.

Most controversially, the UK has sought to remove the European court of justice from its role in enforcing EU law in Northern Ireland, and to have a system of “dual recognition” that would allow goods with differing Brussels and UK standards to circulate freely side by side. Goods not compliant with EU rules would be clearly labelled as “NI-only”.

While the EU will not be able to swallow those proposals, in Whitehall the expectation is that Šefčovič’s proposals will be substantive and not easily dismissed.

Speaking this week, Šefčovič told an audience in Dublin that he hoped the political rhetoric around the issue could be dialled down. “I believe that the package of practical solutions we are putting on the table would be attractive.”

Frost has suggested there is a short window of opportunity in which to strike a deal once the EU proposals are tabled. “We need a short and intensive negotiation, and when I say short, I mean weeks, three weeks,” he said.

Both sides wish to find agreement by the end of the year. Sources suggested that even if notice of article 16 was given in November, talks could continue to see if an alternative is within reach.

Diplomatic sources said a risk to the smooth running of the talks was the sour relationship between the two sides on a range of other issues which diplomatic sources said were at risk of “bleeding” into the Northern Ireland talks.

On Friday, the French EU affairs minister, Clément Beaune, mocked a Daily Mail headline suggesting that French fishers would blockade UK ports before Christmas over the lack of permits being issued to EU vessels to the coastal waters on the south coast of England and around Jersey. But he also reissued France’s threat of retaliating through the terms of the trade and cooperation agreement, and bilaterally, over the UK stance on fishing access.

Beaune said: “Reducing supplies [of electricity to Jersey] is possible, but cutting the power to every Jersey resident this winter is something that will not happen and something that I do not want.

“They made a mess of Brexit. It’s their choice and their failure, not ours. It was a bad choice, we see that today. It is not by creating problems for our fishermen … that you will solve the problems of shortages of Christmas turkey.”