President George W Bush signed legislation today to build 700 miles (1,126 km) of fencing along the US-Mexican border, an election-year move against illegal immigration aimed at helping Republicans.
The measure was bound to anger Mexico. Mexican President-elect Felipe Calderon had said this month the move would "enormously complicate" relations with the United States.
Democratic National Committee spokesperson Luis Miranda
Republicans hoped the legislation would give them an election-year boost as they try to head off a strong Democratic attempt to take control of the US Congress.
"We have a responsibility to secure our borders. We take this responsibility seriously," Mr Bush said in a signing ceremony in the White House Roosevelt Room.
Mr Bush had long opposed supporting a bill that was limited to border enforcement, spending months in a failed attempt to persuade the US Congress to back a comprehensive measure that would include a guest worker program for illegal immigrants.
The Senate had approved a measure he preferred, but Republicans in charge of the US House of Representatives insisted on border enforcement only, feeling election-year heat from Americans upset about the impact of illegal immigration in their states.
In his remarks, Mr Bush insisted a guest-worker program would ease pressure along the border, and said Americans must face the reality that millions of illegal immigrants already live in the United States.
"We must reduce pressure on our border by creating a temporary worker plan. Willing workers ought to be matched with willing employers to do jobs Americans are not doing on a temporary basis," he said.
The 700 miles (1,126 km) of fencing would run along parts of four southwestern states, California, Arizona, New Mexico and Texas. The US-Mexican border runs about 2,000 miles (3,200 km).
The legislation did not provide funding for the fencing, but simply authorized its construction. Part of the funding for the fence, $1.2 billion, was included in a homeland security bill he signed earlier this month.
Congressional Republicans had passed the legislation weeks ago but held off sending the legislation to Bush for signing so it could be used as an election-year tool.
Democrats called the legislation a political stunt.
"By abandoning comprehensive immigration reform and embracing election-year political stunts, President Bush and Republicans in Washington have once again put the interests of their party above the interests of the American people," said Democratic National Committee spokesperson Luis Miranda.