Ukip leader Paul Nuttal has been forced to move house due to concerns about his personal safety, the party has said.
It comes after Mr Nutall was engulfed in a scandal over alleged election fraud when he was accused of giving a false address while standing in the Stoke-on-Trent by-election.
He is under investigation by police after he admitted that he had given his address as a property in the town which he had not yet moved into.
That could be an offence as it is illegal to supply false information to the Electoral Registration Officer.
Ukip's chairman said there had been a a series of "concerning incidents" at the Stoke property following publicity around the issue. He added that that election returning officer had been informed.
Ukip's Paul Oakden said: "Since the address of the house Paul Nuttall has been staying at during the Stoke-on-Trent Central campaign was published on social media there have been a series of concerning incidents at or around it.
"The most serious of these was two unknown men attempting to gain access to the house through a rear entrance.
"There has also been hate mail posted through the letter box and other intrusive behaviour including trespassing in the private garden of the premises and attempts to take pictures through windows and the letterbox."