It was a week of unexpected endorsements for the US presidential candidates, who received the support of aging pop-star Cher, Post-it Notes and . . . pigeons.

Here is this week’s list of surprising, improbable and unlikely updates from the American campaign trail.

Messenger pigeons

In what appeared to be a sarcastic tip of the hat to Trump, a flock of pigeons wearing miniature “Make America Great Again” caps were released in Las Vegas on Tuesday, on the eve of the Democratic candidates’ debate there.

The stunt was later claimed by a group calling itself Putin or Pigeons United to Interfere Now, according to an e-mail received by NBC News.

Trump was reportedly infuriated to learn of a recent congressional briefing by US intelligence analysts who said Russia was trying again to meddle on his behalf in the election campaign.

But while a video of the Maga-hatted pigeons quickly went viral, not everyone saw the humor. Rescue group Lofty Hopes, whose Facebook page describes it as “a Pigeon Positive Movement”, decried what it said was “animal cruelty”. The red hats, it said, could interfere with the vision of those wearing them.

Post-it sized philosophy

Democratic candidate Amy Klobuchar got an unexpected bit of help during the debate Wednesday . . . in the form of a Post-it Note.

During the debate, fellow senator and Democratic rival Elizabeth Warren tartly criticised Klobuchar’s health care plan, which she said was sketchy and incomplete: “It’s like a Post-it Note: insert plan here.”

But the Twitter account of the famous yellow stick-on squares quickly came to Klobuchar’s rescue, saying, “It’s not the size of the Post-it Note, it’s the size of the idea” a message the senator lost no time in retweeting.

She added proudly that Post-its, made by the Minnesota-based 3M company, were “invented in my state”.

Does size matter?

Since December, Trump has missed no opportunity to assert that Democratic candidate Mike Bloomberg was literally not up to being president, even nicknaming the 1.73m former New York mayor “Mini Mike”.

After the president asserted on Fox News that Bloomberg wanted to stand on a box during the debate Wednesday, the Democrat’s team wasted no time in clarifying that Bloomberg would do nothing of the kind.

Taller candidates generally do better than their shorter counterparts in US presidential elections, historians say.

Trump claims to be six foot three, though in photos with other men of that height, he appears to fall short.

‘Believe’ in Biden

Legendary singer Cher weighed in on the race Monday, expressing her support for former vice president Joe Biden in two tweets.

“Good luck Today & Everyday @JoeBiden,” she said in one tweet, before adding that he would be an “Honest, Smart, ‘CIVIL’” president.

Cher is no novice in the political arena. In 2016, she spoke at a fundraising rally for candidate Hillary Clinton, blasting Donald Trump as an “idiot” who, rather than wanting to “Make America Great Again,” as his slogan goes, wanted to “make America straight and white.”