Ryan, appearing on NBC's "Today" show, praised Romney, saying: "I've actually really grown to like him quite a bit. I believe he has the exact kind of leadership skills we need to get this country out of the debt crisis we're in."
But Ryan said he hasn't spoken to the former Massachusetts governor about becoming his running mate and said, "I haven't given it much thought."
Ryan said Romney has had some some trouble with conservatives because of compromises he had to make with Democrats in the state Legislature while he was Massachusetts' governor.
"He's going to be a great standard bearer for us in the fall," Ryan said.
Ryan, the chairman of the House Budget Committee, defended his budget proposal against criticism it would hurt poor people.
The non-partisan Center on Budget and Policy Priorities found 61 percent of its $5.3 trillion in non-defense budget cuts over 10 years would come from "programs that serve people of limited means."
Ryan said the plan wouldn't hurt poor people.
"We don't agree that throwing more money at failed programs works," he said.
NBC said Ryan's budget, which passed the Republican-controlled House, would reduce spending more than $6 trillion in the next decade through cuts and reforms to entitlement programs such as welfare and food stamps.
President Barack Obama has called the proposal, which is unlikely to pass in the Democrat-controlled Senate, a "Trojan horse" and "thinly veiled social Darwinism."
Ryan labeled the president's comments "more petulant than presidential."