The second report published by a World Anti-Doping Agency (WADA) independent commission said that the world governing body's senior officials must have known about state-supported doping within Russian athletics.

Elected last August after pledging "the very highest level of vigilance with regard to doping", Coe's credibility has taken a battering with each new development in the scandal.

As recently as Wednesday, the 59-year-old two-time Olympic champion explicitly rejected allegations of a cover-up, telling Sky in a televised interview: "Was there a cover-up? No."

The new report begs to differ and although commission chairman Dick Pound backed Coe, present for Thursday's WADA press conference in Munich, the former golden boy of British athletics remains in a precarious position.

As IAAF vice-president from 2007 to 2015, Coe was a member of the IAAF Council, which the report said "could not have been unaware" of malpractices concerning doping.

Coe has previously said that the role involved only 10 days' work a year, but Pound believes that he and fellow vice-president Sergey Bubka -- who Coe beat to the presidency -- should have known what was going on.

"Coe and Bubka were there," Pound told British newspaper The Times recently. "They had an opportunity a long time ago to address issues of governance."

Coe initially tried to confront the scandal head-on, branding allegations in the British and German media that the IAAF had turned a blind eye to hundreds of suspicious blood samples a "declaration of war".

Athletics, he said, could not have done more to wipe the scourge of doping from the sport, but after WADA's first report revealed evidence of endemic doping by Russian athletes, his discourse became more nuanced.

During an uncomfortable three-hour grilling by British politicians at London's Houses of Parliament last month, he admitted: "I probably might have chosen different language."

Coe responded decisively to the revelations about Russia in the first WADA report, banning the country from international competition, and has warned that other countries could also face bans.
                  
- Nike role -                  
                  
But his decisions and declarations on other matters have raised questions about his judgement and integrity.

He stepped down from his paid role as a Nike ambassador after being accused of lobbying disgraced predecessor Lamine Diack to hand the 2021 World Championships to Eugene, the American city with close links to Nike.

Coe denied the allegation, but French prosecutors are investigating the process.

Meanwhile, Coe's close aide Nick Davies stepped aside over allegations he discussed delaying the identification of Russian drug cheats prior to the 2013 World Championships in Moscow.

Davies, who is being investigated by the IAAF's ethics commission, denies wrongdoing.

Coe described Diack as his "spiritual leader", only for the 82-year-old Senegalese to be arrested by French police over claims he took one million euros ($1.1 million) in bribes to cover up positive drug tests.
Diack's son, Papa Massata Diack, was last week banned for life by the IAAF's ethics commission for blackmailing athletes, along with two high-ranking Russian officials.

But in his appearance before British MPs, Coe said he had never even heard "whispers" about corruption within the organisation.

As Coe fights to preserve his reputation and safeguard the future of his sport, memories fade of his 1980s glory days, when he won gold in the 1,500 metres at the 1980 and 1984 Olympics.

His achievements in politics and sports administration have been just as stellar, with highlights including a five-year stint in Britain's parliament and a stunning success as head of the 2012 London Olympics.

Publicly, Coe insists that he has had no thoughts about standing down and Pound said on Thursday that he "can't think of anyone better" to lead the IAAF out of its crisis.

They were welcome words for Coe, but above his head the thunder continues to rumble.