Mr Ryan said he welcomed the fact that Mr Cox was giving his endorsement to pro-Europe candidates in these crucial elections.
"This is an important endorsement from such a distinguished and experienced European as Pat," he said.
Mr Cox said : "This is not a national election but it is to elect people to the European Parliament and I would urge people to vote and continue their preferences for candidates who are unequivocally pro-Europe to represent Ireland in the Parliament."
"I would also encourage people to do this in the context of the forthcoming Lisbon Treaty referendum," he said.
"I have no hesitation in asking voters to exercise their preferences for pro-Europe candidates," said Mr Cox.