Former US president George Bush hits brother Jeb's campaign trail in South Carolina
Former US president George Bush will be campaigning for his younger brother Jeb in South Carolina, marking his most direct entry into the 2016 White House race to date.
George Bush won a bruising South Carolina presidential primary on his way to the Oval Office, as his father did before him.
But for Jeb Bush, the most consequential foreign policy decisions of his brother's time in office are suddenly front-and-centre of his bid to keep alive his campaign for the 2016 Republican presidential nomination - thanks to rival Donald Trump.
Brash billioniare businessman Mr Trump, the Republican front-runner, used the final debate before the state's February 20 primary as an opportunity to excoriate George Bush's performance as commander-in-chief.
The former president, he said, ignored "the advice of his CIA" and "destabilised the Middle East" by invading Iraq on dubious claims that Saddam Hussein had weapons of mass destruction.
"I want to tell you: they lied," Mr Trump said. "They said there were weapons of mass destruction, there were none. And they knew there were none."
And Mr Trump did not let up as Mr Bush tried to defend his brother, dismissing his suggestion that George Bush built a "security apparatus to keep us safe" after the 9/11 attacks.
"The World Trade Centre came down during your brother's reign, remember that," Mr Trump said, adding: "That's not keeping us safe."
The onslaught - which Jeb Bush called Mr Trump enjoying "blood sport" - was the latest example of Mr Trump's penchant for mocking his rival as a weak, privileged tool of the Republican Party establishment, special interests and well-heeled donors.
But the exchange also highlighted the former Florida governor's embrace of his family name and history as he jockeys with Florida senator Marco Rubio and Ohio governor John Kasich to emerge from South Carolina as the clear challenger to Mr Trump, who won the New Hampshire primary, and Texas senator Ted Cruz, the victor in Iowa's caucuses.
The approach tacks away from Mr Bush's months-long insistence that he is running as "my own man", but could be a perfect fit for South Carolina. Noted South Carolina senator Lindsey Graham, who ended his Republican presidential campaign in December and endorsed Jeb Bush in January, said: "The Bush name is golden in my state."
George Bush retains wide appeal among Republicans, from evangelicals to chamber of commerce business leaders and retired members of the military. All are prominent in South Carolina, with Bush campaign aide Brett Foster going so far as to say that George Bush is "the most popular Republican alive".
The attack on George Bush carries risk for Mr Trump, given the Bush family's long social and political ties in South Carolina and the state's hawkish national security bent, bolstered by more than half a dozen military installations and a sizeable population of veterans who choose to retire in the state.
Mr Trump has repeatedly defied predictions that his comments might threaten his perch atop the field. And as he jousted with Mr Trump, Jeb Bush said: "This is not about my family or his family."
But the Bush family does have a history in the state that is hard to overlook. In 2000, George Bush beat John McCain in a nasty contest, marred by rumours that Mr McCain had an illegitimate black child - Mr McCain adopted a child from Bangladesh.
Exit polls showed George Bush won nearly every demographic group.
His father George Bush senior, the 41st president, won twice in the state, beating Bob Dole in 1988 and demolishing Pat Buchanan in 1992.
Meanwhile, Hillary Clinton and Bernie Sanders were in Las Vegas as they campaigned ahead of next weekend's Democratic caucuses in Nevada.
The former US secretary of state and the Vermont senator spoke at Victory Missionary Baptist Church in the city.
Mrs Clinton was accompanied by civil rights campaigner, congressman John Lewis of Georgia. His appearance was a continuation of Mrs Clinton's efforts to woo black voters, which has intensified following her 22-point loss to Mr Sanders in last week's New Hampshire primary.
Both Nevada and South Carolina, which follows the Western state on the Democratic primary calendar, are more racially diverse than lead-off Iowa and New Hampshire.