Until he was selected as the Libertarian Party's candidate for president, Bob Barr was best-known as one of the leaders of the attempt to impeach President Bill Clinton.
But in 2008, the former Republican congressman could inadvertently help the Democrats re-take the White House, by splitting the conservative vote.
Mr Barr became disaffected with President Bush's anti-terror policies
Mr Barr represented Georgia's seventh congressional district for the Republicans from 1995 to 2003.
While in the House of Representatives, he served as a senior member of the Judiciary Committee, as Vice-Chairman of the Government Reform Committee, and as a member of the Committee on Financial Services.
Drawing on his prior experience as a federal prosecutor, Mr Barr introduced a resolution calling on the Judiciary Committee to consider impeachment proceedings, even before allegations about Bill Clinton's relationship with White House intern Monica Lewinsky had surfaced.
And once the scandal broke, he was the first lawmaker to call for President Clinton's resignation.
Mr Barr later wrote about the Clinton impeachment in his 2004 book "The Meaning of Is: The Squandered Impeachment and Wasted Legacy of William Jefferson Clinton".
He was also an author and a sponsor of the 1996 Defence of Marriage Act, which ensured that the federal government would only recognise marriages between a man and a woman.
Although thought of as one of the more conservative members of the House, Mr Barr did not always toe the Republican party line.
Following the 9/11 attacks, he was a vocal critic of some of the Bush administration's anti-terrorism proposals, and managed to insert a number of "sunset clauses" - time-limits - into the Patriot Act.
His objections to what he saw as increasing attempts by the White House to crack down on individual liberties and privacy led to his 2004 decision to leave the Republican Party and endorse the Libertarian Party's presidential candidate.
He subsequently began distancing himself from a number of his former party's key policies, speaking out against the war in Iraq and the "war on drugs", as well as stepping up his attacks on the administration's anti-terror policies.
By 2006, he was a fully-fledged member of the Libertarian Party, describing himself as "a proud, card-carrying Libertarian".
The party, like the Republican Party, believes in reducing the size of government and lowering taxes, but Libertarians favour a more liberal approach than most Republicans on social issues like gay marriage and drug legalisation.
Mr Barr has high hopes of picking up disaffected Republican voters, especially in his home state of Georgia, and neighbouring southern states, as well as some north-western states with strong libertarian traditions.
Indeed, Democratic presidential hopeful Barack Obama's campaign chief David Plouffe has said that he expects Mr Barr to pick up some 4% of the vote in Georgia, and as much as 8% in independent-spirited Alaska.
With polls suggesting that Mr Obama is faring better in these traditionally Republican states than Democrats have done in previous years, Mr Barr could take just enough voters from Republican candidate John McCain to tip Georgia and Alaska into the Democratic column.
And although a Democratic victory would not be Mr Barr's preferred outcome, by helping to bring it about, Mr Barr would be fulfilling at least one of his goals - punishing a Republican Party that he believes no longer holds true to conservative values.