NEW YORK • Mr Donald Trump has suggested during a rally in Pennsylvania that Mrs Hillary Clinton was not "loyal" to her husband, former president Bill Clinton, an insinuation about their relationship that plunged the 2016 presidential race further into a personal battle.

Mr Trump told the crowd in Lancaster County, about 110km west of Philadelphia, that Mrs Clinton's only loyalty was to her donors and herself. He added: "I don't even think she's loyal to Bill, you want to know the truth. And really, folks, really, why should she be, right?"

The Republican, who gave no evidence to support his aspersion, spoke on Saturday night, a day after he told The New York Times he was prepared to attack his Democratic rival over her husband's well-publicised infidelities before and during Mr Clinton's presidency.

In the interview, he called her an "enabler" and accused her of attacking the women with whom Mr Clinton had affairs.

Mr Trump has struggled to move past a widely panned performance last week in his first debate against Mrs Clinton. But he has simply repeated criticisms of her regarding her husband, as well as attacks on a former Miss Universe whom Mrs Clinton mentioned during their debate as someone Mr Trump had once belittled.

Mr Trump, whose first marriage ended in a deeply public and tabloid-focused affair with the woman who became his second wife, Ms Marla Maples, told The Times that infidelity had never been an issue for him.

At other points during the rally, the tycoon reprised his claims from August, during another difficult stretch of his campaign, that there was vote-rigging in "certain areas" of Pennsylvania - again without proof - and he urged his supporters to monitor polling places in those sections of the state.

The remarks have been seen as a reference to places populated by minorities.

For Mr Trump, who is trailing badly in polls with women, the new attack on Mrs Clinton is a risky strategy. At the weekend rally, he also repeated his criticism from the debate that she lacked the stamina to be president, a comment that many women viewed as sexist.

To make his point, he mocked her stumble at a Sept 11 memorial event, when she left early with what her doctor described as a bout of pneumonia. He swooned back and forth at his lectern and then walked away from it, pretending to lurch forward.

"Here's a woman, she's supposed to fight all of these different things, and she can't make it 15 feet to her car," Mr Trump said. "Give me a break."

NY TIMES