Beatrix von Storch said the European Commission president’s push for a ‘United States of Europe’ was “tragic” and needed to be stopped “immediately”.
Mr Juncker delivered his much-anticipated State of the Union speech on Wednesday with a snub to Britain by insisting the EU will move towards greater integration despite Brexit.
Speaking to Express.co.uk in Strasbourg, Ms von Storch, deputy leader of the far-right Alternative for Deutschland party, which is part of the Europe for Freedom and Democracy group in the EU parliament, labelled the speech “frightening”.
She added eastern member states would be next to follow the UK out of Europe.
She said: “I think his whole speech was an historic one. He was going against all the good guys and he was declaring the United States of Europe. It was frightening what he came out with today.
“The European Union which has been presented to us today is not the one we want to be members of.
“But I think it will be difficult to set it up that way because imagine the eastern states and I think they will be the next to follow the Brits out of the European Union.
“You could see him as a person today acting like a dying man with the last vision of something which is about to explode. I think it was to some extent tragic.”
Asked how long the EU could survive in its current form, she added: “It has to be reformed immediately.
“They will change the European Union to the United States of Europe without treaty change. Without the change of the treaties. This is incredible what we have heard today.”
Meanwhile, Hans-Olaf Henkel, vice-president of the European Parliament’s third-largest group the European Conservatives and Reformists, said Brexit was a “big disaster” that Mr Juncker was ignoring.
Speaking to Express.co.uk, Mr Henkel said the UK’s decision to leave the Brussels bloc would be just as bad for the EU as Britain.
He said: “He called it a full vision of Europe. I must say, it was more a fools’ vision of Europe because he seemed to have totally ignored the realities of Europe.”
Philippe Lamberts, co-leader of The Greens-European Free Alliance group said he “had his doubts” over the European Commission president, whose five-year term expires in 2019.
Mr Juncker, who began speaking at 8am this morning, set out his 12-month masterplan to steer the troubled bloc through the escalating refugee crisis and reform the eurozone.
Keen to push ahead with his masterplan, billed as the biggest reboot in the EU’s history, Mr Juncker ratcheted-up the federalisation of the 60-year-old bloc’s core economies.
The Brussels boss has also called for European Union integration in the face of rising populism after Britain voted to sever ties with the bloc ahead of crunch elections in Italy, Sweden, Hungary and the Czech Republic, where eurosceptic parties are gaining momentum.
It appears Jean-Claude Juncker is keen to make his mark in the EU as his five-year term as European Commission president expires in 2019 with a grand masterplan to rebuild the bloc, left in tatters after Britain’s momentous decision to leave.