Philadelphia, Pennsylvania - Barbara Pierce Bush, daughter of Republican ex-president George W. Bush, has endorsed Democrat Kamala Harris in the razor-thin White House race and campaigned for her over the weekend, she told People magazine.

Bush spent part of the weekend knocking on doors for the vice president's campaign in Pennsylvania, considered one of the most crucial swing states that will decide the November election between Harris and Republican Donald Trump.

"It was inspiring to join friends and meet voters with the Harris-Walz campaign in Pennsylvania this weekend," she told People. "I'm hopeful they'll move our country forward and protect women's rights."

The 42-year-old has been described as an independent, but her family is of course Republican royalty – her late grandfather George H.W. Bush also served as president.

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A small but vocal group of prominent Republicans, turned off by Trump's extreme rhetoric on subjects ranging from abortion to migration and democracy, has endorsed Harris.

George W. Bush, who was in the Oval Office from 2001 to 2009, has so far refused to endorse a candidate in 2024, and has remained tight-lipped on politics throughout much of his post-presidency.

But Harris has already won the support of his vice president Dick Cheney – the architect of the Iraq war – and his daughter, former Republican Congresswoman Liz Cheney, who has campaigned with Harris.

Barbara Bush, whose fraternal twin sister Jenna works for NBC, has been outspoken on her abortion views and rallied in the past for Planned Parenthood, the country's leading reproductive health organization and advocacy group.

Trump has boasted that his picks for Supreme Court justices paved the way for the overturning of Roe v. Wade and the end of federal protections for abortion access, which led to at least 20 states bringing in full or partial restrictions.