London: A former Special Forces soldier is rounding up supporters for a leadership bid against Ed Miliband if he does not win the General Election, The Mail on Sunday has learned.

Dan Jarvis, who entered the Commons only four years ago, has told potential supporters he is prepared to run if Miliband fails to dislodge David Cameron from No 10.

One senior Labour MP, who met privately with Jarvis in the Commons a month ago, said: “Dan wants to go for it if the result is disappointing. I thought about it for a couple of weeks, then rang him to say he could count on my backing.”

The news has emerged as the Labour leader faces the embarrassment of two senior party figures openly debating his failings during a broadcast interview this week.

With polling day barely six weeks away, Rochdale Labour MP Simon Danczuk will discuss Miliband’s lack of voter appeal with party peer Lord Glasman. During the debate, Danczuk asks: “What has Nigel Farage got that Ed Miliband doesn’t?” The peer — a former adviser to Miliband — responds: “He has got the ability to sit in the pub and be at his complete ease, which is a very magical gift. Ed is from the seminar room.”

Jarvis, the Shadow Justice Minister, is rapidly gaining support on the party back benches as a `clean skin’ candidate who, unlike many rivals, was not an adviser or minister during the Blair or Brown governments and is `untainted’ by association with Miliband’s inner circle. Some MPs also argue that the 42-year-old ex-Para’s military career — a rarity in Labour ranks — would be more appealing to voters than Miliband’s background as a policy adviser.

In any leadership contest, Jarvis is likely to face the more experienced figures of health spokesman Andy Burnham, Shadow Home Secretary Yvette Cooper, Shadow Business Secretary Chuka Umunna, education spokesman Tristram Hunt and ambitious frontbencher Liz Kendall.

The backer added: “Dan has a clear view of his own strengths, and an even clearer view of his rivals’ weaknesses.”

Jarvis became the first person since the Second World War to resign a military commission to contest a by-election. He successfully stood in Barnsley Central in 2011, shortly after his wife Caroline died of cancer, aged 43, leaving him to care for their two children. Jarvis has since remarried and now has a third child.

The former major spent 15 years in the Paras, and was awarded an MBE after serving in Afghanistan, Iraq, Kosovo and Sierra Leone. In keeping with his action-man image, it was reported last week he had pacified a drunken thug wielding a bottle who demanded his wallet.

Under party rules, if Miliband fails to win power in May but doesn’t resign, a leadership election can be triggered only if 20 per cent of the party’s MPs nominate a specific challenger. The winner, elected by MPs, MEPs, party members and unions, would be announced at the party’s next annual conference.