A Republican Senate candidate compared Michelle Obama to a chimpanzee during her meeting with the Queen and urged the former first lady to stand up “straighter”.
Karin Housley – currently a state senator who serves in Minnesota – took to Facebook in 2009 to compare Ms Obama to the chimpanzee in 1951 film Bedtime for Bonzo, which starred Ronald Reagan.
“Michelle is soooo far from cool. Don’t we expect our first ladies to at least stand up straight? (And my dear sister, know the proper etiquette and DO NOT TOUCH THE QUEEN!),” Ms Housley wrote in the post.
“I do miss Nancy Reagan. Ronald even more. Speaking of Bedtime for Bonzo, I think even that chimp stood up straighter than Michelle. Uh-oh, someone is going to make a comment.”
Jake Schneider, who is the Housley campaign spokesman, said the "out-of-context" Facebook post was being used to “manufacture outrage” after it came to light.
“This is what the radical left does when they are losing - they attack Republicans so they don’t have to come up with solutions to the problems Minnesotans are facing,” Mr Schneider said in a statement.
Ms Housley is running against Democrat Senator Tina Smith for the seat that was held by fellow Democrat Al Franken, who resigned in January amid allegations of sexual misconduct.
Ms Smith is leading Ms Housley in the polls by an average of nearly ten points, according to RealClearPolitics.
Ms Housley made an on-stage appearance with US president Donald Trump at a “Make America Great Again” event in Rochester, Minnesota, earlier this month.
Ms Obama, America’s first black first lady, endured repeated racism while in the White House. From being branded an “ape in heels” by a West Virginia official to being told she had a “gorilla face” by a local Washington mayor, she was subject to numerous spiteful racially-charged remarks from politicians and commentators.
The 54-year-old, who married Barack Obama in 1992, addressed the racism she has experienced during an appearance in Denver last year.
Ms Obama, who enjoyed consistently high popularity ratings while first lady, was pressed about which shards of glass had cut her deepest during her eight years in the White House and referred to the incident cited above where she was called an “ape in heels”.
"The shards that cut me the deepest were the ones that intended to cut," the Chicago native replied. "Knowing that after eight years of working really hard for this country, there are still people who won't see me for what I am because of my skin colour."
She added: "Women, we endure those cuts in so many ways that we don't even notice we're cut. We are living with small tiny cuts, and we are bleeding every single day. And we're still getting up."
Ms Obama addressed the persistent “shadows” of racism in a speech at Jackson State University - a historically black institution in the capital of Mississippi - in 2016. She began by citing personal, quotidian examples of racism before going on to address macro-level structural prejudice.
Ms Obama talked of being pulled over for “driving while black”, being closely scrutinised while shopping and even having random passers-by actively cross the street to avoid coming into contact with you. But then she drew attention to institutionalised forms of racism.
She said: "Maybe it’s when the early voting location in your neighbourhood just happens to be closed, or law after law is passed about the kind of ID you need to cast your vote. Maybe it’s all those schools that, despite the laws, are still very much separate and unequal. Or the criminal justice system that still doesn’t provide truly equal justice for far too many!”