see following article:
http://news.bbc.co.uk/2/hi/uk_news/politics/3752750.stm"While there is a political dimension to the issue, the US request for British troops to move north in Iraq to take over from US marines is probably more connected to operational problems.
Indeed, the US request is hardly something Mr Bush would want to shout about. It exposes the weakness of US forces in south central Iraq that they have to ask an ally for help.
The British government is going through a two-stage process. The first is to consider the military implications and, if those are resolved, the second will be to consider the political fall-out.
But the request has probably little to do with President Bush wanting allied back-up at this crucial stage of his election campaign...."