Boris Johnson's remained father Stanley has applied to stand in the EU elections.
Mr Johnson Senior, who appeared on I'm A Celebrity...Get Me Out Of Here, said he was worried the Tories would not "make the most" of the opportunity.
He told LBC Radio: "I think the idea that we should be talking down these Euro elections is absurd.
"If we're staying in we may as well do what is required and fight the elections. And if we're going to fight the elections we might as well fight to win, I'm speaking as a Conservative.
"And as Conservatives I think we should have a really constructive role to play out there."
He went on to say that by Thursday, following Theresa May's crunch summit in Brussels tomorrow, the UK will know whether we'll be staying in the EU long enough to take part in the elections.
He said: "I'm saying don't let's be gloomy about this. It's happening. It will happen and let's make the most of it.
Mr Johnson, himself a former member of the European Parliament, went on to describe how he came to the decision to throw his hat in the ring.
He said: "I sat up night - I didn't sat up all night, I sat up at least an hour and a half - and jolly well I wrote out why I think it is worth doing."
