Rising mortgage rates could cost the Tories 45 seats in their southern heartlands, analysis shows.
Research by Public First casts doubt on whether the Conservatives could hold onto a string of constituencies where they have modest majorities and above average numbers of mortgage holders.
Mortgage rates shot up after Liz Truss's disastrous mini-Budget amid fears the Bank of England would hike interest rates to manage the flurry of unfunded tax cuts.
Figures released by Moneyfacts show the average two and five-year fixed mortgage rates on offer is 6.53% and the average five-year fixed rate is 6.36% - the highest since 2008.
New Chancellor Jeremy Hunt has ripped up £32billion worth of tax cuts as the Tories scramble to calm the market.
Analysis of outstanding mortgage debt by local authority has identified hotspots where people are vulnerable to rising interest rates.
Leafy Esher and Walton in Surrey, represented by ex-deputy PM Dominic Raab, and Culture Secretary Michelle Donelan's Chippenham constituency are among those at risk.
The analysis also flagged Boris Johnson's Uxbridge and South Ruislip seat, and Altrincham and Sale West, in Greater Manchester, represented by 1922 Committee chief Graham Brady.
"While Southern constituencies are typically (though not always) relatively affluent, high house prices mean that households are likely to be relatively leveraged," the research says.
"If other factors do not push voters away from the incumbent party in these constituencies, higher interest rates may be the straw that breaks the camel’s back."
Rachel Wolf, founding partner at Public First, who co-wrote the 2019 Tory manifesto, said: “The impact of mortgage rates rising could be even worse for people, in many areas, than rising energy bills.
"People think this is because of the government’s decisions, and it opens up another political opportunity for Labour and the Lib Dems – particularly in Southern constituencies where households are more likely to have mortgaged themselves to the hilt."
