Bush Clan Has No Plans to Back Donald Trump

America's most prominent Republican family, the Bushes, are declining to endorse Donald Trump for president, handing the GOP presumptive nominee an early setback in his efforts to unite a fractured party.

Former presidents George W. Bush and George H.W. Bush, who undoubtedly bristled at Trump's bullying attacks on candidate Jeb Bush, signaled through their offices that they will stay on the sidelines during this cycle.

The elder Bush has endorsed every Republican nominee in the past five elections, but he does not have plans to endorse Trump in 2016, his spokesman Jim McGrath told the Texas Tribune on Wednesday.

"At age 91, President Bush is retired from politics," McGrath told the paper. "He came out of retirement to do a few things for Jeb, but those were the exceptions that proved the rule."

The 41st president's son Jeb Bush dropped out of the race in February.

Jeb's brother George W. Bush "does not plan to participate in or comment on the presidential campaign," his personal aide Freddy Ford told the paper.

Trump has launched bitter attacks on George W. Bush during this year's campaign. In February he called Bush's decision to invade Iraq "one of the worst decisions in the history of the country," and said the Bush administration "lied" about Saddam Hussein possessing weapons of mass destruction.

Jeb Bush, who exited the race that month, endorsed Ted Cruz in March, and has said Trump would lose in a landslide if he were the nominee to go up against Democrat Hillary Clinton in the general election.

George W. Bush's former chief of staff, Andrew Card, said Thursday that Trump has to become more respectful about the party's leadership and show greater "maturity" about handling tough decisions if he wants Republicans to coalesce around him.

"Donald Trump's got a lot of work to do to earn my vote, and to earn the confidence of people who are leaders in the Republican Party," Card, now the president of Franklin Pierce University in New Hampshire, told MSNBC.

If the election were held today, "I'd probably write in a name," Card said.