Bush signs bill to build border fence to stop Mexicans

President George Bush has signed a bill authorising 700 miles of fencing along the US-Mexican border, a pre-election gift to his tough-on-immigration white conservative base, but one that risks alienating America's growing Latino population and straining US-Mexican relations.

The Secure Fence Act is the relatively meagre product of almost a year of fractious debate about America's swelling army of immigrant workers, of whom up to 12 million are illegal. President Bush wanted a temporary worker programme and a path to residency and citizenship for those already in the country.

But that stance put him at odds with conservatives in Congress who wanted to brand all undocumented foreigners as felons and deport them. It also became a major reason why conservative Republican voters, especially in the border states, have become disillusioned with the Bush White House. In the end, beefing up border security was the only issue on which agreement was possible.

Yesterday's signing, after the collapse of numerous efforts to produce a comprehensive package of new immigration laws, was deliberately timed to be as close to the 7 November mid-term elections as possible. The bill passed the House and Senate at the end of September and could have been on the President's desk four weeks ago.

Now it has clearly become part of the Republicans' campaign to hold on to their congressional majorities and energise a voting base that has shown signs of preferring to stay at home this election season. "We have a responsibility to enforce our laws," President Bush said at the signing ceremony. "We have a responsibility to secure our borders. We take this responsibility seriously."

Theoretically, the fence will be built along the most common border-crossing areas in California, Arizona, New Mexico and Texas. So far, however, only $1.2bn has been earmarked for its construction; the total cost is estimated to be up to $9bn.

That raises the question of whether the fence will ever be built. Experts have also questioned whether it would have any significant effect in deterring border-crossers; the head of the union representing Border Patrol agents said this week that he thought it would slow migrants only by "a minute or two".

It is also unclear how successful a tough-on-immigration stance can be with the broader electorate. The Republicans actually risk losing one House seat on the Arizona border because their candidate, Randy Graf, is perceived to be too extreme on immigration. Many Latino advocacy groups, including reliably conservative ones previously courted by President Bush, have expressed deep misgivings and thrown their energies into endorsing Democratic candidates in key races.

The proposed border fence also poses a major threat to bilateral relations with Mexico. Mexico's outgoing President, Vicente Fox, has described the idea as "shameful" and likened it to the Berlin Wall.

Mr Fox and President Bush started with a close relationship that has slowly unravelled as their mutual hopes evaporated for instituting a guest worker programme, and ending the deadly games between migrants and Border Patrol officers.