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James Carville had harsh words for Ralph Nader who is trying to recruit a primary challenger to run against President Obama.

Yesterday Nader told the LA Times that Obama should “welcome” the challenge, “because nothing’s worse than an incumbent president slipping in the polls, being constantly on the defensive, being accused by supporters of having no backbone.”

But Carville doesn’t think a primary challenge is the answer to the president’s problems.

“Don’t you think Ralph Nader has done enough damage to the country? I mean, he was probably single handedly responsible for electing George Bush,” the Democratic strategist said on “GMA.” “Maybe the man should consider retiring.”

Carville has been critical of Obama’s administration but he thinks Obama should “fire a lot of people” - specifically his economic advisors – and change the administration’s direction.  Today he stood by those words.

“They can’t have the kind of year that they had so you are just going to keep doing things the same way we did it. You’ve got to do things differently. That happens in every organization,” he said.

But Obama’s tough stance yesterday on reducing the debt by $2 trillion was a good start, Carville said.

“What they can do is between now and the election and I think yesterday was a start toward that. I think if he shows that kind of aggressiveness and he makes some changes in some personal and gets some different people in there I think he can do quite a bit better but it was pretty bad,” he said.

Watch the interview here:

– George Stephanopoulos