The UK Independence Party more than tripled its vote share at the Newport West by-election, rising from 2.5% in 2017 to 8.6%.
UKIP Leader Gerard Batten said,
"I would like to thank Neil Hamilton and his team who worked tirelessly during the campaign, and send special thanks to Christine Hamilton who supported Neil in her usual dedicated way.
"If there is a General Election now, UKIP will cause mayhem in marginal seats, and that is exactly what UKIP will do.
"The political establishment is betraying Brexit, and the next test will be the English and Northern Irish local elections on May 2nd. Also, if Article 50 is extended, we will face another European Parliament election. UKIP is ready to fight whatever may come, and we will punish the political establishment for betraying Brexit.
"UKIP is the only pro-Brexit party that also represents a domestic political threat to the political establishment."