A tearful Paul Nuttall has asked UKIP members to back him after what he called a "cruel and evil smear campaign".
Mr Nuttall has faced a backlash and calls to quit as an MEP after it emerged that claims he lost close personal friends in the 1989 Hillsborough tragedy were false.
But speaking at his party's conference in Bolton, Mr Nuttall, who is fighting a by-election next week, said he would not allow those attacking him to "break me" or "break UKIP".
Mr Nuttall appeared to cry as he asked party members if they backed him - and was met with a standing ovation.
He said: "Many people will notice that I've had a bit of a difficult week.
"This is two-fold, actually. Firstly, I take the blame for the fact that I failed to check what was up on my website in my name, that was my fault and I apologise.
"But I will not apologise for what is a coordinated, cruel and almost evil smear campaign that has been directed at me.
"It is based on lies from sources who have not been named. It has been a tough week for me but I will not allow them to break me and I will not allow them to break UKIP."
Looking up at the audience, he said: "I was also asked by two journalists yesterday if I still have the support of my party."
His words were met with a standing ovation and large cheers from the party faithful as one man in the crowd shouted "take that".
Removing his glasses and appearing to wipe a tear from his eye, Mr Nuttall said: "Thank you, I'm a bit overwhelmed. Thank you."
In his address, Mr Nuttall laid out his vision for UKIP - pledging to cut foreign aid, reduce taxes and put more money into health and housing.
He pledged to take domestic energy bills and hot food out of VAT, a move he said would make the traditional British dinner of fish and chips "cheap as chips again".
After the speech, Mr Nuttall refused to answer further questions about Hillsborough when he left the stage.
Escorted by security guards through a crowd of journalists, Mr Nuttall refused to say anything about comments made by millionaire UKIP donor Arron Banks.
Mr Banks has said he is "sick to death of hearing" about Hillsborough, and accused some of "milking" the tragedy.
The UKIP leader said simply: "I've said absolutely everything I have got to say on the subject", adding: "I was at Hillsborough, I've got witness statements."
(c) Sky News 2017: Tearful Paul Nuttall asks UKIP members for support