Columbia, South Carolina: Republican presidential hopeful John McCain has promised the biggest showdown of his battle-scarred career if he is elected to office, pledging to chase Osama Bin Laden "to the gates of hell".

The Vietnam veteran wrapped up his bid to win Saturday's South Carolina primary by insisting that he would not only root out the head of Al Qaida but lead the US to victory in Iraq.

"My friends, I want to stand before you now and tell you that if I have to follow him to the gates of hell I will get Osama Bin Laden and I will bring him to justice. I will get him!" He repeated the sentiment to standing ovations at several rallies.

The hawkish McCain tells audiences he is the only candidate with the "background, experience and judgment" to have advocated the troop "surge" in Iraq at an early stage. "We are succeeding in Iraq, we are succeeding, but we live in a dangerous world," is a typical refrain.

Romney bats for scribes

To hear Mitt Romney tell it, the reporters covering his presidential campaign are worse off than the candidate. "We don't treat them real well," Romney told Tonight Show TV talk show host Jay Leno during a taping on Friday. "The guys that follow us in the presidential race come in a whole group. We put them in the back of the aircraft. We feed them lousy food. We wake them up early in the morning to go to events ... we don't give them chairs to sit on, either. So they have a tough go of it, but they're doing their job."

Romney, the former Massachusetts governor who is seeking the Republican nomination, had a run-in with a reporter. Romney's assertion that lobbyists don't run his campaign drew a sharp response from the reporter who pointed out that a lobbyist was a prominent adviser. On Friday, Leno asked Romney: "Have you ever lost your cool? Have you ever just exploded at a guy?"

"Absolutely, but not a reporter. That's sort of the end of the campaign when that happens," said Romney. "Sometimes the kids push me to the edge, but I learned not to lose my cool with the kids."