A Tory MP said she has "muted" Cabinet member Nadine Dorries on Twitter after she criticised Rishi Sunak for wearing expensive clothing.
Dorries, who remained devoutly loyal to Boris Johnson as he fell from power, has gone on to back Liz Truss to succeed him as Prime mininster, over fellow rival Sunak.
Taking aim at Sunak on Monday, Dorries tweeted a newspaper report that the former chancellor had stepped out on the campaign trail wearing a bespoke suit worth £3,500, and later wore a pair of £450 Prada loafers on a visit to Teeside.
The culture secretary tweeted that in contrast, Truss wore a pair of earrings which cost £4.50 from Claire's Accessories.
She said: "Liz Truss will be travelling the country wearing her earrings which cost circa £4.50 from Claire Accessories.
"Meanwhile… Rishi visits Teeside in Prada shoes worth £450 and sported £3,500 bespoke suit as he prepared for crunch leadership vote."
The comparisons of the pair have added to growing toxicity amid the leadership vote, which has been blighted by allegations of a briefing war and repeated clashes over policy and the pair’s records.
Angela Richardson, the MP for Guildford and a Sunak supporter, responded to Dorries’ tweet by replying: “FFS Nadine! Muted.”
And Cabinet Office minister Johnny Mercer said the leadership contest was becoming "embarrassing", warning that on the "current trajectory" their party would be "out of power in two years time."
He said: "Back in Whitehall today - perhaps only a few weeks to make a difference.
"Probably worth remembering that on current trajectory we are out of power in two years time.
"The puerile nature of this leadership contest is embarrassing. Time to raise the standards."
Truss and Sunak will go head-to-head in a TV debate on Monday after the battle to become the next prime minister became toxic with the two rival camps clashing over immigration, China and the economy.
The BBC debate at 9pm comes after a weekend that saw allies of the two Tory leadership hopefuls trade increasingly personal attacks.
In a previous televised debate, Sunak took aim at his rival's political past, saying she had previously been “both a Liberal Democrat and a remainer” and claimed her proposed policies for unfunded tax cuts were socialist.
Truss chose to compare her upbringing to Sunak's, who came from great personal wealth and attended the costly Winchester College public school.
In comparison, Truss attended a Leeds comprehensive.
She also claimed his tax policies risked pushing the UK into a recession.
The studio audience will be made up entirely of people who voted Conservative at the last general election.
With postal ballots set to arrive on Tory members’ doorsteps by 5 August, Sunak faces pressure to use the BBC debate – and another hosted by TalkTV and the Sun on Tuesday – to make an early breakthrough.
Although he comfortably won the leadership race among Tory MPs, bookmakers have made Truss favourite after a series of opinion polls and surveys put her firmly ahead with Conservative members.