Several top UKIP figures including deputy leader Margot Parker quit, urging Bolton to step down following a no-confidence vote in his leadership.
In Britain, the deputy leader of UKIP is one of several senior party figures to have resigned over leader Henry Bolton's refusal to step down.
Margot Parker quit on Monday after the party's national executive committee backed a vote of no confidence against Bolton. Soon after, UKIP's immigration spokesman John Bickley also handed in his resignation.
By the middle of the day they had been followed by the party's spokespeople on education, trade, fisheries, local government and London.
Bolton has come under fire because of texts sent by his ex girlfriend Jo Marney who said Prince Harry's fiancee Meghan Markle would "taint" the Royal Family. Her text messages led to accusations of racism.
Despite splitting with Marney soon after her comments, Bolton - UKIP's fourth leader since the Brexit referendum - is under mounting pressure to go. However, he has so far refused to budge, insisting another leadership contest will finish the anti-EU party.
His stance may force the party to hold an emergency meeting of ordinary party members next month, to stage a vote on his leadership.
Bolton's relationship with Marney came under investigation by the party after he left his wife for the model late last year.
Under Nigel Farage, the UK Independence Party played a significant role in building support for the country’s departure from the European Union, culminating in the successful 2016 referendum. However, backing at the polls has since plummeted, and its level of support is estimated in the low single figures.