President Obama delivered a forceful defense of his health care law at a press conference Friday afternoon, daring congressional Republicans to force a government shutdown over their plans to defund the law.

He called the 40 House votes to repeal Obamacare an "ideological fixation" and added: "There's not even a pretense that they're going to replace it with something better."

Why was Obama so aggressive? Because he knows he has the political high ground on the issue. We explain in this "In Play" clip.