If anything was going to derail John McCain’s White House bid, it was the fear that he was too old to be president, not the likelihood of being embroiled in a sex and favours scandal. But when the Arizona senator reached for the lawyer who steered Bill Clinton through his women troubles, it was a sign that he was seriously rattled.

At the moment that the race was shaping up to be an epic contest between Barack Obama and McCain – the future versus the past, as Obama would have it, or naivety versus experience, as McCain prefers to frame it – the scandal hit the newsstands. After an early, highly successful counterattack, McCain was accused this weekend of being economical with the truth as far as some aspects of the story were concerned.

The essence of the tale is fairly simple. Vicki Iseman, 40, a blonde telecommunications lobbyist, became friends with McCain, 71, eight years ago. Some advisers thought the relationship might be romantic.

There is no evidence of an affair but they were certainly cosy. Iseman accompanied him to fundraisers, travelled with him on a client’s jet and appeared to trade on her relationship with him to such an extent that McCain’s senior advisers warned her to back off.

A race like a crackpot Dynasty

The contest between Barack Obama and Hillary Clinton matches any fiction

Multimedia

• Full coverage: US elections

• Pictures: race for presidency

Background

• The ascent of Barack Obama, Mr Charisma

• Decay, jobs and guns fall under the spotlight

• Free trade: Clinton/Obama's mistakes

Adding spice to the story, Iseman appears to resemble McCain’s wife, Cindy, another pencil-thin blonde, who stood by her husband last week as he repeatedly denied both the sexual innuendo and specific allegations of favours in the story.

John Weaver, who was once one of McCain’s closest aides but quit his campaign last summer, said he remembered meeting Iseman at Washington’s railway station and asked her to keep her distance from McCain, a member of the Senate commerce committee. He was concerned that Iseman’s boasts would damage McCain’s reputation because he had taken such a prominent stand against special interests and lobbying.

Two anonymous former associates of McCain said they confronted the senator several times about the risk to his career of showing favouritism towards Iseman. McCain wrote letters to the Federal Communications Commission (FCC) that were helpful to her clients, although there were other times, staff say, when he took a stand against their interests.

The thinly sourced tale had been knocking around The New York Times for months before it decided to publish, causing fury on the right that it had timed its onslaught last week to coincide with McCain’s all-but-declared victory in the Republican nomination battle.

Trying to besmirch a Vietnam war hero on the question of his universally acknowledged integrity was regarded as a low blow, unworthy of the staid Gray Lady, as The New York Times is known. If this were a British political sex scandal, it would be regarded as only a matter of time before McCain was cast into a pit of shame as new revelations inevitably appeared. But McCain was given so much warning of the story that he was able to mount a ferocious counterattack.

By the end of last week the contention by the McCain camp that the article was a fabricated “hit-and-run smear campaign” was widely accepted. That it came from The New York Times, which had recently endorsed McCain for the Republican nomination, was an added bonus.

McCain’s popularity with the liberal media – his “base”, as it is jocularly known – has long aroused the mistrust of conservatives. Here at last was a chance for him to join forces with the right against a common enemy.

“Even if they want to quibble within our own tribe, they’ll circle the wagons when we’re attacked by the [New York] Times,” said Charlie Black, a senior adviser to McCain.

McCain used his victimisation as grounds for a fundraising appeal to conservatives. “Well, here we go,” wrote Rick Davis, his campaign manager, in an e-mail to supporters. “We need your help to counteract the liberal establishment.”

The campaign went on to announce that it had recorded its best 24 hours in online fundraising. McCain, however, was not celebrating yet. “We still don’t know how this whole thing ends up,” he said cautiously.

Republicans read with a shudder a column in The New York Times on Friday by David Brooks, one of the newspaper’s few conservative columnists, who is close to McCain and his team. Although Brooks claimed to have no special knowledge about the identity of the sources who allegedly confronted McCain over Iseman, he wrote: “At his press conference Thursday, McCain went all-in. He didn’t just say he didn’t remember a meeting about Iseman. He said there was no meeting. If it turns out that there is evidence of an affair and a meeting, then his presidential hopes will be over.”

So far nothing has surfaced on that score. But McCain made other claims that are unravelling this weekend concerning a meeting with Lowell “Bud” Paxson, then head of Paxson Communications and a main McCain donor.

The company was a client of Iseman seeking to buy a television station in Pittsburgh, but had been stalled by the FCC.

McCain insisted last week that he did not meet Paxson or Iseman before sending two letters to the FCC urging their help.

But Newsweek revealed that McCain gave a sworn deposition in a lawsuit in 2002 contradicting this assertion.

“I was contacted by Mr Paxson on this issue,” McCain noted at the time. “He wanted their approval very bad for the purposes of his business. I believe that Mr Paxson had a legitimate complaint.” He went on to declare: “I’m sure I spoke to [Paxson]” and admitted that the letters he wrote on his behalf could possibly have the “appearance of corruption”.

A spokesman for McCain said the senator had been “speaking in shorthand” and meant that his staff had been contacted by representatives of the company. But Paxson emerged from retirement this weekend to claim that he did indeed meet McCain several weeks before the controversial letters were written. He also seemed to recall that Iseman was present. “Was Vicki there? Probably,” Paxson told The Washing-ton Post. “The woman was a professional. She was good. She could get us meetings.”

If McCain’s account of his relationship with Paxson is untrue, it raises the possibility that he may be blagging his way through other bits of the story.

When Mitt Romney, the former governor of Massachu-setts, was still in the presidential race, aides began to whisper that McCain’s candidacy was flaky. They knew The New York Times was working on the Iseman story.

Romney hung on in the primary campaign as long as he could but eventually decided to stop throwing good money after bad from his own pocket and withdrew. If McCain’s campaign collapses, the Republicans will be stuck without a presidential candidate (not counting Mike Huckabee, the former pastor, who is still around but has lost his claim to be a serious contender).

Matthew Dowd, a former adviser to President George W Bush, said the story helped Obama, if only indirectly. “Every day that the news is being dominated by John McCain’s troubles is a bad day for Hillary Clinton,” he said. “And every day that isa bad day for Clinton is a good day for Barack Obama.” The closer Obama is to clinching the Democratic presidential nomination, the more he is being subjected to a barrage of negative commentary.

At this late stage, Clinton’s best chance of a comeback rests on stories dragging Obama down. But if voters are not paying attention, they are unlikely to come to her rescue in time.

After his landslide victory in the Wisconsin primary last week, Obama is finally being subjected to the kind of scrutiny that Clinton’s camp has been calling for all along. Three themes are being developed by conservatives: that the “Obamessiah” is unpatriotic, self-obsessed and the most left-wing candidate in decades with a serious shot at the presidency.

It was a point made by Karl Rove, Bush’s former adviser, in The Wall Street Journal last week. “For Mr Obama, words are merely a means to hide a left-leaning agenda behind a cloak of centrist rhetoric,” he wrote.

McCain has already started to adopt the same line of attack against Obama as Clinton, by accusing him of being naive on foreign policy and deploying “eloquent” but empty rhetoric.

“When I was a young man, I thought glory was the highest ambition and that all glory was self-glory,” he said pointedly. “I do not seek the presidency on the presumption that I am blessed with such personal greatness that history has anointed me to save my country in its hour of need.”

There has been internet chatter for months that Obama once neglected to put his hand on his heart while saying the pledge of allegiance. His wife Michelle aroused the wrath of conservatives last week by saying: “For the first time in my adult life I am proud of my country because it feels like hope is finally making a comeback.” The comment appeared to confirm suspicions that the Obamas did not share the patriotic fervour of ordinary Americans and judged the country a success only now that it was willing to send them to the White House.

McCain’s wife Cindy, who rarely engages in political point-scoring, spotted an opportunity. “I’m proud of my country,” she said at a rally. “I don’t know about you – if you heard those words earlier – I’m very proud of my country.” It was all going so well until her next appearance – in the position of loyal wife with possibly errant husband at a press conference.

Peter Wehner, a former White House adviser to Bush, has detected a “slightly narcissistic quality” to Obama but believes he is a “pretty cool and pretty balanced guy”, despite the rock star adulation he is receiving. Accusations of vanity and self-obses-sion will “only be a problem if they are true”.

He believes the way to defeat Obama is to attack him for being a conventional liberal (the American term for a left winger). “America is not a liberal country and that is going to be one of his biggest weaknesses.” It will still not be easy for McCain to win, he stressed. “McCain’s strength is not domestic or economic issues, but he is extremely strong on national security.”

A story conservatives are hoping will gain traction concerns the relationship between Obama and Bill Ayers and his wife Bernardine Dohrn, former members of the Weathermen, the 1960s terrorist group.

Ayers and Dohrn went on the run in 1970 – while McCain was being held prisoner in the “Hanoi Hilton” – and surrendered a decade later. Charges against them for participating in the Weathermen’s bombing campaigns were dropped because of unlawful FBI surveillance. It emerged last week that Obama visited their house in Chicago for a meeting in the mid1990s where he was introduced as a potential candidate for the Illinois state senate. He went on to serve with Ayers on the board of a Chicago foundation.

Clinton would love to see more stories on the Ayers connection, but the media is unlikely to make too much of it until Obama is nominated. And for now, all eyes are on McCain’s potential sex scandal rather the vulnerability of his Democratic rival.

Video: Michelle Obama says she is proud of her country

Video: Cindy McCain replys that she has always been proud of her country

Video: McCain wins in Wisconsin

Times Recommends

• Obama: the world can expect better of America
• Gulp! Mystery killer threatens French oyster
• Secret of Northn Lights key to space safety