Hyde-Smith has come under additional scrutiny in the intervening days after a photo showing her wearing a replica hat of a Confederate soldier made the rounds on social media, as did a video in which she mused about making it harder for "liberal folks" to vote.
She also urged voters to disregard polls showing Republican Senator Cindy Hyde-Smith leading by as many as 10 percentage points, pointing to her upset primary win against outgoing Representative Michael Capuano.
Trump was in Biloxi to stump for Hyde-Smith (R-Miss.), who faces former Clinton cabinet official Mike Espy (D-Miss.) in a Tuesday runoff election.
Another sign referred to the race between appointed Republican Sen.
State Capitol police did not immediately respond to multiple requests for comment.
Despite Hyde-Smith's comments on "public hangings", and other ties to an allegedly racist past, her chances of winning another term as a U.S. Senator representing the state of MS are promising. "If he invited me to a public hanging, I would be on the front row".
The matter is under investigation by the Mississippi Department of Public Safety, Mississippi Capitol Police and the US attorney's office.
Espy is African-American.
Neither candidate has commented on the nooses.
U.S. Attorney Mike Hurst says his office is working with law enforcement partners and will investigate if a federal crime occurred.
MS has a history of racially motivated lynchings and violence against people who sought voting rights for black citizens.
Civil rights activists were beaten and killed in MS as they pushed for African-American voting rights, particularly from the end of the Second World War until the 1960s.