The US President has welcomed vice presidential pick Paul Ryan to the 2012 race, while issuing a critique of his policies.

Barack Obama delivered his first remarks towards Mitt Romney’s new running mate, and despite boos from the crowd, he was very positive about Ryan as a person.

"Just yesterday morning, my opponent chose his running mate, the ideological leader of Republicans in Congress, Mr Paul Ryan. I want to congratulate Mr Ryan. I know him, I welcome him to the race," the President said.

He added: "Congressman Ryan is a decent man, he is a family man, he is an articulate spokesman for Governor Romney's vision."

However, Obama said he fundamentally disagrees with Romney and Ryan's vision.

He said: "It's an idea propagated by the other side that somehow we are going to grow this economy from the top down and that if people at the top are doing really really well then everybody else is automatically going to benefit.

"Now, this kind of top down economics is central to Governor Romney and it is central to his running mate."