A growing campaign to upgrade the A1 has been boosted by business chiefs issuing a rallying call for support. Liberal Democrat leader Ming Campbell also backed demands for improvements.
Nearly 2,500 people have added their names to an online petition on the Prime Minister's website calling for the route to be upgraded to dual carriageway between Berwick and Morpeth.
Northumberland MPs Alan Beith and Peter Atkinson, along with the Duke of Northumberland, are among those to have backed the petition that is being signed by hundreds every day.
And the North-East Chamber of Commerce (NECC) has now taken the unusual step of contacting all its 4,400 members to lobby the Government by supporting the petition.
Liberal Democrat leader Ming Campbell has urged people to back the online protest, which is calling for improvements on safety and economic grounds.
NECC membership and policy director Andrew Sugden said: "It is an unusual move for NECC to call on its members to act in this way, but for many years now we have been calling for crucial improvements to our North-South corridors, most recently in the high-profile Go For Jobs campaign in conjunction with The Journal.
"This petition provides a perfect platform for North-East business people to add their voice to the call for essential improvements to this crucial artery."
He said: "We sent this call to arms to all our members because this isn't just a Northumberland issue, it's such a significant route for the entire region.
"We would urge businesses, wherever they are based, to take five minutes out to back the petition." Mr Campbell said: "I drive that road from time to time so I don't need any persuasion about the need for a dual carriageway."
Sir Ming said it was "probably not appropriate" for him to sign the petition, but stressed that its objective had his support.
"I welcome the petition and, as my colleague Alan Beith has been assiduous in promoting this case, I am happy to support it.
"It is an opportunity for people who use the road and perhaps even those who don't to express their support," the Lib Dem leader said.
He said there was no comparison between the A1 as it was and the M6 and upgraded M74 link between England and Scotland on the western corridor.
Sir Ming also supported the proposal to widen the Gateshead Western bypass to three lanes to tackle congestion and he "unequivocally" supported a £600m modernisation of the 30- year-old Tyne and Wear Metro, a proposal for which is currently being studied by the Government.
Referring to the Metro, he said: "The risk of course is that if it isn't improved then it will simply drive people on to the roads - and that is a thing we are trying to avoid, both for road safety and for environmental reasons."