Labour is to kick off campaigning in a string of upcoming byelections by highlighting increased mortgage costs in so-called blue wall constituencies, in a tactical shift in which the party will openly target Conservative-held seats coveted by the Liberal Democrats. Rachel Reeves, the shadow chancellor, is to visit Kingswood, the constituency vacated by Chris Skidmore, the Conservative who quit as an MP last week in protest at the government’s planned new rounds of oil and gas licences. Reeves will highlight a Labour analysis of rising mortgage costs in 42 constituencies identified as being in the blue wall, a Lib Dem-coined term for relatively affluent seats, generally Tory held and often in commuter belts around cities. On Reeves’s visit to Kingswood, just outside Bristol, she will say more than 100,000 households in the 42 constituencies will have mortgages that need renewing this year, with the bulk facing steep increases in payments. As well as highlighting the continued repercussions of the fiscal crisis sparked by Liz Truss’s brief time in government, the choice of blue wall constituencies for the analysis, including top Lib Dem targets such as Esher and Walton, Wimbledon and Winchester, shows a new Labour confidence that they can attract disaffected centrist Conservatives. A Labour source said last year’s Mid Bedfordshire byelection, where the party saw off a strong Lib Dem challenge to take the formerly firm Conservative seat, showed there were now “no no-go areas for us”. “In Mid Beds we could have rolled out the yellow carpet and told the Lib Dems: ‘We’ll leave you to it.’ But we fought them and won. It shows quite how far we have come in such areas since 2019. “The job for Rachel and Keir has been to convince voters they can trust us on the economy, that we take fiscal discipline seriously.” The mortgage analysis, based on data from the Bank of England and the House of Commons library, estimates that among 111,600 mortgages due for renewal in the 42 seats this year, 2,800 are in Kingswood. Labour said that while the average monthly repayment for families formerly on fixed-term mortgages had risen by £240, given higher average house prices in blue wall seats, for these areas the average could be nearer £385. While the date for the Kingswood byelection has not been finalised, it is expected in mid-February, most likely on the same day as one in Wellingborough, Northamptonshire, triggered after enough local voters supported a recall petition for the sitting Tory MP, Peter Bone. This happened after Bone was suspended from parliament for six weeks after a watchdog found he had bullied a staff member and exposed his genitals near their face. Reeves said: “Homeowners across Britain, including many lifelong Tory voters, have been left worse off after 14 years of economic failure. “The aftershocks of the Conservatives’ disastrous mini-budget that crashed the economy and sent mortgage rates soaring continue to be felt for thousands of hard-pressed families.”