Former US president Richard Nixon once famously said of his downfall over the Watergate scandal that it was not the crime that killed you, but the cover-up. To err is human, even in politics. To lie about it - and get caught - is infinitely worse, especially in politics. An adviser to former president Bill Clinton took delight in reminding the Republican Party of Nixon's remark this week. The White House has good reason to remember it as the party campaigns to retain control of Congress in elections next month. It will rue a failure to live up to its claim to be more attuned to Americans' moral values. The 'crime' in question here is Republican congressman Mark Foley's sexually explicit e-mails and text messages to teenage congressional aides. That Mr Foley, a known homosexual, was chairman of the House of Representatives missing and exploited children's caucus added to the embarrassment. After his activities were exposed, Mr Foley resigned and checked himself into a clinic for treatment for alcoholism. At that stage the scandal may have been politically manageable, until aides claimed that House of Representatives' Speaker Dennis Hastert had known about the situation for three years and done nothing to protect boys as young as 16. Mr Hastert has apologised and a congressional ethics committee has begun hearings into Mr Foley's activities. US President George W. Bush made Christian moral values a divisive issue in his successful bid for re-election in 2004. Forsaking the moderate middle ground in a lurch to the right, the Republicans adopted a hardline stance on issues such as abortion, gay marriage and embryonic stem-cell research. It paid off in shoring up base support in conservative strongholds in the vast American heartland. But it was a risky strategy that further antagonised the Democrat half of the country. Nonetheless, it was dusted off for Mr Bush's bid to retain Republican control of Congress in next month's elections. White House political strategist Karl Rove planned a campaign that cast the Republicans as tougher than the Democrats on fighting terrorism, more attuned to Americans' values on moral issues and more likely to be good for the economy because of their commitment to tax cuts. It was a simple, clever strategy that played on fear, prejudice and greed. The aim was to turn around Mr Bush's low approval ratings. They have been battered by issues such as the mismanagement of the response to the hurricane that destroyed New Orleans, high petrol prices, continuing bad news from Iraq, a revolt by senior Republicans against Mr Bush's plans to override the Geneva Conventions in the treatment of terror suspects, and tapping of Americans' phones without warrants in the 'war on terror'. But the strategy was beginning to unravel even before the teen aides' scandal broke. Just when Mr Bush was stepping up the rhetoric about the administration's toughness against terror, a leaked national intelligence assessment concluded that far from being a front against terrorists, the Iraqi war has fuelled Islamist extremism around the world. And a new book by Bob Woodward, the Washington Post editor who exposed the Watergate scandal, has sewn doubts over the administration's vigilance against terrorism and described it as deceitful and dysfunctional over the Iraqi war. With much of their core strategy mired in controversy, the Republicans may be forced to campaign on their economic credentials. A speech that Mr Bush was due to make today in the Washington area about economic improvements driven by tax cuts could be a foretaste of the thrust of his campaigning to come. The moral high ground has proved to be shaky. Failure to hold it may yet leave the Republicans facing the loss of core, socially conservative support and the prospect of a Democrat-controlled Congress that will probe the legality and morality of the Bush administration's actions in the 'war on terror' and the Iraq invasion. If political debate now shifts back to the middle ground, America and the world will be better places for it.