George W. Bush joins Jeb Bush's presidential campaign in South Carolina

U.S. Former President George W. Bush on Monday hit the campaign trail in South Carolina in a bid to boost his brother Jeb Bush's teetering campaign in this crucial early voting state.

In his most political speech since leaving office in 2009, George W. Bush called on voters to choose a "measured and thoughtful" candidate and a candidate with humility for the 2016 presidential election.

"I understand that Americans are angry and frustrated, but we do not need someone in the Oval Office who mirrors and inflames our anger and frustration," said the former president. "We need someone that can fix the problems that cause our anger and frustration, and that's Jeb Bush."

During his 20-minute speech, Bush did not mention Donald Trump for once, but he left no doubt that apart from giving a boost to his brother's troubled campaign, his campaign debut was also meant to deliver a blow to the New York billionaire developer notorious for his blunt language and dismissal of "political correctness."

"Strength is not empty rhetoric. It is not bluster. It is not theatrics. Real strength comes from integrity and character," said former president Bush. "And in my experience, the strongest person isn't usually the loudest person in the room."

"All the sloganeering and all the talk doesn't matter if we don't win," he added.

George W. Bush's rare emergence from political hibernation came at a time when Trump took several swipes at his two poisonous legacy of an unpopular war in Iraq and the economic recession that began at the end of his presidency.

Tensions between Jeb Bush and Trump boiled over on Saturday at the last Republican primary debate, in which the real estate mogul blasted former president Bush's national security record and said it was under Bush's watch that the World trade Centers in New York fell on Nov. 9, 2001. Endi