Grassley, who as a lead negotiator of the bipartisan healthcare reform deal the president supports has dealt often with Obama, said that while he likes the president personally, Obama effectively only had two years of experience in national politics.
"I think that he is a good person, and good-intentioned," Grassley, the ranking member of the Senate Finance Committee, said in a radio interview. "But I believe he didn't serve in government long enough to understand really how things work."
"Remember, he was in the Senate four years, but effectively only two years because he spent two years where he was hardly ever here at all -- he was campaigning for president," Grassley said. "He really does not have an understanding of how Congress operates."
Grassley said that while the president's numerous advisers may help him understand the process, Obama still has a "tough time."
Still, Grassley did save some praise for Obama's personal skills, though.
"You can't help but like the guy," the Iowa Republican said. "As he's talking to you, he looks you right in the eye, and you're the most important person in the world. He's not like a lot of politicians."
"He's very idealistic, and so when you're idealistic you want to put all those things into practice," Grassley added. "So I think he's maybe trying to do too much at one time."