Ex-Republican aims for presidency

Bob Barr left the Republican Party, saying he was disillusioned

A former Republican congressman, Bob Barr, has announced he hopes to run for president of the United States - for the Libertarian Party.

"I've heard from Americans from all walks of life... they want a choice," said Mr Barr, announcing his candidacy.

The Libertarian Party, a small group with limited support, will choose its presidential runner later this month.

But the US political system is dominated by the two major parties, which enjoy almost all support.

As a result, third-party candidates tend to run the risk of being little more than a sideshow.

However, Mr Barr, 59, hopes many voters will be drawn to his plans to slash government spending, withdraw from Iraq and halt immigration.

"They believe that America has more and better to offer than what the current political situation is serving up to us," he said.

Threat to McCain?

Mr Barr, who was a congressman for Georgia from 1995 to 2003, left the Republican Party two years ago saying he was disappointed by its failure to shrink the role of government.

He was also disillusioned by the Bush administration's readiness to undermine civil liberties as part of its fight against terrorism, he said.

The Libertarian Party, which believes in fiscal conservatism and limited government, will pick its candidate at its national convention in Denver, starting on 22 May.

Mr Barr is the clear favourite to win that nomination, says the BBC's Jack Izzard in Washington.

Winning the White House is quite another matter though - he would need a miracle for that, our correspondent says.

Nonetheless, he may prove a major thorn in the side for the Republican candidate John McCain.

Some right-wing voters may be tempted to switch to Mr Barr - which could cost the Republicans dear, our correspondent adds.