Rupert Cornwell: Why this tragic case is the only story in Washington

How is it, the world beyond America must wonder, that a debate over whether a single brain-damaged woman in Florida should be removed from life support has driven Congress in Washington to prepare a specific bill to save her and send President George Bush scurrying back to the White House to sign it? The answer is in part genuine belief, but in at least equal part, raw politics.

The case of Terri Schiavo is unfolding in a country whose sharpest divisions are less economic or even social as cultural, where the dominating issues are not wages, deficits and jobs, but lifestyle issues such as abortion, gun control and gay marriage.

It is unfolding, moreover, when conservatives on all those issues are clearly in the ascendant - as Mr Bush's victory and the sweeping Republican Congressional gains last November only underscore.

"I hope we're not turning this human tragedy into a political issue," John McCain, the senior Republican Senator from Arizona, declared on one of the Sunday talk shows yesterday. Some hope. For conservative Republicans, the case is a perfect opportunity to advance their cause, extending the pro-life argument into new terrain, and placing the Democrats squarely on the back foot.

Indeed, according to the Washington Post, Republican strategists have circulated a memo among the party's senators, arguing that the Schiavo case offers "a great political issue" that could galvanise Christian conservatives ahead of the 2006 mid-term elections. The memo explicitly noted that the Florida Democrat Bill Nelson, whose seat Republicans have targeted next year, refused to sponsor this weekend's emergency legislation.

For Democrats, an opposite argument applies. By agreeing to a limited bill to save Ms Schiavo, the party hopes to correct the public impression, which cost it dear in the recent election, that it is too liberal and out of touch with ordinary America.

Not only grand political strategy, but also individual ambitions and interests are at play. By no coincidence, the campaign to save Terri Schiavo campaign is being led in the House by Tom DeLay, the second ranking Republican, who is embroiled in a fund-raising scandal in his native Texas and alleged lobbying irregularities in Washington. For Mr DeLay, known as 'The Hammer,' this is a precious opportunity to change the subject - and perhaps save his job.

Nor is it a co-incidence that the two Republicans leading the fight in the Senate - the majority leader, Bill Frist from Tennessee, and the youthful and very conservative Rick Santorum of Pennsylvania - are both known to be mulling Presidential runs in 2008, and both are courting Christian conservatives for all they are worth.