But some Labour backbenchers are more interested in another aspect of Mr Kennedy's background: his role in the early 1990s as a leading British defender of the Serbs during the Bosnian war.
Calum MacDonald, the Labour MP for the Western Isles, who has campaigned for years on behalf of the Bosnian Muslims, has written to Brian Mawhinney, the Conservative party chairman, demanding that he disassociates the party from "a supporter of extreme nationalist Serbs".
Mr Kennedy sat next to Radovan Karadzic, the Bosnian Serb leader, at a press conference in July 1992, a summary of the meeting in the House of Commons shows. Karadzic has since been indicted by the United Nations war crimes tribunal on charges of genocide.
The first accusations of ethnic cleansing of the Bosnian Muslims by the Serbs had been made in the spring of 1992. But Karadzic claimed that it was the Serbs who were being exterminated.
Karadzic later compared the Tory candidate for the West Midlands marginal to Francois Mitterrand, the late president of France, and described Mr Kennedy as "an expert on Yugoslavia" whose dialogue with Serb leaders had made a "decisive contribution to the humanitarian relief process".
Mr Kennedy said yesterday he had nothing to apologise for. Radovan Karadzic had praised him for helping open Sarajevo airport - a move that had benefited civilians on all sides, he said. Mr MacDonald was a "Bosnian activist" who did "not have the support of all the Labour Party".
"Some people are just obsessed with what happened three or four years ago," Mr Kennedy said. "I had my point of view and he had his. There is peace now and it is time to move on to other things."
Mr Kennedy has never excused ethnic cleansing, and said last year that war criminals should be tried.
It was his concern for the fate of the illegal Serb "republic" in Bosnia that pushed him into international affairs between 1991 and 1993.
John Kennedy was born John Gvozdenovic, but later added his British mother's maiden name, Kennedy.
"I am officially John Gvozdenovic Kennedy, but to make matters simpler I no longer use my middle name," he explained last year.
A descendant of minor Serb nobility and former member of the right-wing Monday Club, the 30-year-old commodity dealer developed something of a speciality in the use of the world's large pool of exiled royal families in election campaigns.
When Mr Kennedy stood unsuccessfully in Barking in Essex in the 1992 election, he had Prince Idris from the deposed Libyan royal family touring the constituency with him. The connection caused him embarrassment last year when he was caught up in allegations about an attempt to blackmail the prince and claimed that MI5 had been involved in the attempt to smear him. No charges were brought against him.
But it was the Bosnian conflict that brought him to prominence. Before sanctions were imposed on Serbia in 1991, he worked with Ian Greer, a Westminster lobbyist, to promote Serbia and its industries in Britain.
Both men confirmed last year that the public relations work had lasted four months.
Mr Kennedy then visited Serb-held Bosnia, where monarchist sympathies are still strong, and began acting as a defender of the Serbs.
He went in July 1991 to eastern Croatia, which was being seized by Serb forces, and emerged saying that the Serbs were victims too. "The columns of Serb refugees are not a political trick," he said.
In the event it was the Croats who became permanent refugees when the Serbs took control.
On Sky News in May 1992 he said that the Serbs "in no way are aggressors". In letters to the Guardian and the Times he praised the Bosnian Serbs for "moving to end the cycle of violence" and for "appearing to honour their unconditional cease-fire". He argued strongly against giving military help to the beleaguered Bosnian Muslims.
On 15 July 1992 he was on the platform at the press conference with Radovan Karadzic at the House of Commons. The aim of the conference was, according to papers from the Serb Information Initiative, "to give details of concentration-camp sites and detention facilities used for the imprisonment or extermination of Bosnian Serbs".
No evidence of the mass extermination of Serbs was found. But from 1992 onwards there has been abundant evidence of the mass extermination of Bosnian Muslims at the hands of the Serbs.
Mr Kennedy is still seen as an ally in Serbia and was the subject of a glowing profile in the Serb magazine Intervju last July.
The Bosnian embassy remembers him too. "He is our enemy," said a spokesman.
Conservative Central Office said yesterday that it knew nothing about the candidate's background and had no plans to respond to the challenge from the Labour MPs.
Prominent Conservatives in the new Halesowen and Rowley Regis constituency said they had no complaints about Mr Kennedy and dismissed talk of the Bosnian war as nonsense. "He's an excellent candidate," said a local councillor, Dorothy Murdock. "We can't fault him."Reuse content