UKIP leader Nigel Farage told Daybreak that today's result in South Shields was "remarkable".
He said: "People haven't seen us as being relevant for local elections, or in some ways general elections, so for us to be scoring at least 26% of the vote where we stand is, I think, very significant indeed."
When asked about whether the party had now entered a four-party race, Mr Farage replied: "Numerically we're the third [party] because the Lib Dems are trailing behind."
He added: "This wave of protests certainly isn't short term, it's lasting."
More top news
Victoria Beckham's youngest son had his track "If Every Day Was Christmas" premiered on Capital FM on Wednesday morning.
Pfizer and Flynn Pharma broke competition law when they increased the cost of a medicine used by around 48,000 patients in the UK.
Police have released the final messages some of the 36 victims of the Oakland warehouse fire sent to loved ones.