Diane James resigned as the leader of the pro-Brexit U.K. Independence Party on Tuesday after 18 days in the role, citing personal and professional reasons.

"I will not be formalizing my recent nomination to become the new leader of the party," the member of the European Parliament said in a statement posted on her Twitter account.

"It has become clear I do not have sufficient authority, nor the full support of all my MEP colleagues and party officers to implement changes I believe necessary and upon which I based my campaign."

James succeeded Nigel Farage as UKIP's leader in September and pledging at the time to ensure that the Conservative government did not negotiate a soft Brexit.

The UKIP could not immediately be reached for comment.