The US seems to be losing interest in the Sussexes, with the couple’s popularity at a swift decline, according to an opinion poll.

The pair, formerly well-liked among Americans since making the US their home, has plummeted in popularity since Harry’s memoir Spare hit shelves last week, the Sun reported.

The autobiographical book has quickly become the fastest-selling, non-fiction piece in literary history.

However, despite successful book sales, a Redfield & Wilton poll of 2000 US voters indicates a serious decline in ratings for the Sussexes.

It reveals Harry now has an approval rating of -7, a stark contrast to his rating of +38 at the beginning of December.

And his wife Meghan Markle dropped to -13, in comparison to her +23 rating over the same time period.

When the poll subjects were asked whether Harry’s decision to reveal intimate conversations between him and his family members in his book was the right thing to do, only 26 per cent agreed.

The pair, formerly well-liked amongst Americans, have plummeted in popularity since Harry’s memoir Spare hit shelves last week. Photo / Andrew Warner

One of Harry’s more shocking admissions in the memoir was that Prince William knocked him to the floor during a spat regarding Meghan.

William allegedly labeled the former Suits actress as “rude” and “difficult” before grabbing Harry by his shirt collar and breaking his necklace, resulting in the Duke of Sussex falling to the floor.

• Iran accuses Prince Harry of war crimes
• Jeremy Clarkson apologises over Markle column, likely to be dropped by Amazon
• UK Correspondent: It's clear Clarkson crossed the line in column about Markle

Prince William and Harry allegedly came to blows during a spat regarding Meghan. Photo / AP

Harry states he was left with visible wounds on his back after falling onto his dog’s bowl and breaking it.

The duke also admitted to doing cocaine on multiple occasions, smoking cannabis during his time at Eton and experimenting with magic mushrooms.

What’s more, the prince divulged in his memoir how he lost his virginity to an older woman with an affinity for horses — behind a pub in a field.

Harry also slammed his stepmother Camilla labelling her dangerous and “a villain” over her relationships with the press.

However, it appears the biography and Harry’s subsequent interviews have warranted no change in opinion for some, with around 37 per cent of Americans not wavering in their support of the Sussexes.