Labour's North East heartland would be laid waste if the Heywood and Middleton by-election result was repeated at next May’s general election.
In the Thursday vote, UKIP gained 9,801 votes and Labour lost 6,866 in what it saw as one of its North West strongholds.
If the same losses and gains happened in the North East, it would mean 11 out of 27 Labour seats would go to UKIP.
The seats would include two in Newcastle, two in Middlesbrough - and even Tony Blair’s former constituency in Sedgefield could be lost. But the biggest threat appears to be in South Shields.
It was won in a 2013 by-election by Emma Lewell Buck after David Miliband stood down, with Ukip coming second. That began a trend of strong by-elections for Nigel Farage’s party. If it repeated its success at Heywood and Middleton, it would score a convincing victory in South Shields.
Earlier this month, UKIP won the Westoe ward in a South Tyneside Council by-election.
Political expert Dr Martin Farr from Newcastle University said: “The Heywood result shows that, even with a safe seat and an established party machine in place, Labour is vulnerable without an effective leader and a clear message. That is something UKIP has and Labour do not.”
However Dr Farr added: “There is still a chance UKIP could implode before then. There are enough banana skins they can create, like calling for the banning of everyone with Aids from entering the country.
“But it has showed that UKIP is now a challenge to Labour in the North and the Tories in the south. Anyone who does not think that now is out-of-date.
“However it might suffer the Lib Dem disease of always coming second, as UKIP has done in about the last seven by-elections except in Clacton.”
Our calculations showed that across the region Labour seats could topple if UKIP maintain support.
In Northumberland, Wansbeck seat would go while in Tyne and Wear, Newcastle Central, Newcastle North and South Shields would fall to Ukip.
Further south, Bishop Auckland, Darlington, Hartlepool and Sedgefield would go, then on Teesside, Stockton North, Middlesbrough and Middlesbrough South and East Cleveland would fall to Nigel Farage’s party.
Dr Martin Farr added: “I don’t think come the general election UKIP will win so many seats - if any - in the North East, but it is certainly food for thought for Ed Miliband.”