George Bush relatives may back Clinton as Trump tells early voters to change ballot

Meanwhile, George Bush and his father could "potentially" vote for Hillary Clinton, the nephew and grandson of the former US presidents has said.

George P Bush, the son of Mr Bush's brother Jeb, said he was the only member of his powerful Republican political dynasty who would be voting for the Grand Old Party (GOP).

His remarks came as he was addressing a small Republican rally in San Marcos, Texas.

Pressed later to clarify his comments, Mr Bush said of grandfather George HW Bush and uncle George W: "I don't know how they voted. I'm speculating, to be honest."

Asked if either could vote for Democratic presidential candidate Mrs Clinton, Mr Bush, a land commissioner, answered: "Potentially. But hard to speculate."

Former Florida governor Jeb Bush was defeated by Donald Trump in the Republican presidential primary.

Meanwhile Mrs Clinton said Mr Trump had "no excuse" for not releasing his tax returns and called on him to do so before the November 8 election.

She said she was particularly interested in learning about any dealings Mr Trump has had with Russian interests and whether he contributed to charity.

She told a crowd in Florida that most of those there had probably paid more in federal taxes than billionaire Mr Trump.

Breaking with decades of tradition, Mr Trump has refused to make his tax returns public, citing an ongoing audit, but tax experts say there is no reason why he could not.

Mrs Clinton also attacked Mr Trump's business record, calling him the "poster boy for everything that is wrong with our economy".

But there was no escaping Mrs Clinton's own problems. Senate Homeland Security and Government Affairs Committee chairman Ron Johnson said her choice to blend public and official business on her private email server could be impeachable if she won the presidency.

The Wisconsin senator Johnson told the Beloit Daily News that Mrs Clinton "purposefully circumvented" the law, adding "this was wilful concealment and destruction" involving information related to national defence.

Mr Johnson said under federal law anyone found to have concealed or removed such records would be disqualified from holding office.

The FBI found that classified information had passed through Mrs Clinton's home server but declined to recommend charges.

Mr Johnson is locked in a re-election battle with Democrat Russ Feingold, whom he defeated in 2010.

For his part, Mr Trump urged early voters who have had second thoughts about their presidential choice to recall their ballots and change their minds.

He told supporters that Wisconsin was one of four states in which someone who voted early could potentially change it at a county clerk's office.

He said that voters who "are having a bad case of buyer's remorse" should change their ballot "if you think you made a mistake".

Mr Trump said the four states that allowed early ballots to be changed were Wisconsin, Michigan, Minnesota and Pennsylvania.

In Wisconsin, voters can change their minds up to three times. The deadline for doing so is Thursday. But changing votes is very rarely done, according to the Early Voting Information Centre at Reed College.

Earlier US president Barack Obama told working-class voters not to be "bamboozled" by Mr Trump, saying he had "shown no regard for working people".

Repeating his disbelief, Mr Obama said: "C'mon, this guy?" and added that Mr Trump "wouldn't let you into one of his hotels unless you were cleaning the room".

Mr Obama was campaigning at Capital University near Columbus, Ohio, a state he won twice by winning just enough working-class voters, while pumping up turnout among African Americans.