The presidency is a powerless office except when it isn't

Jose Antonio Vargas, an undocumented immigrant, asked Muñoz during a Google+ Hangout how President Obama feels about deporting 1.5 million illegal immigrants since taking office.

"The government’s job is to do what Congress tells it to do," Muñoz replied. "Congress, under the immigration laws that we've got now, Congress requires us to remove people who are removable and gives DHS, frankly, a whole lot of resources to do that job. DHS’s job is to make sure they make the best possible decisions on how they use those resources."

She said the Department of Homeland Security has tried to prioritize whom it goes after, for example those convicted of crimes, but at the end of the day, Congress needs to pass immigration reform.

"We all understand we are enforcing and implementing a system which is broken, and our primary job here is to fix it and that requires the Congress of the United States," Muñoz said. "That’s something we've been trying to get Congress to do for four years, and our moment has come... We have to drive it home and make sure we get to an outcome."

The number of deportations has increased every year since Obama took office and reached an overall total of 1.5 million at the end of last year.

President Obama's announcement Friday that he is using his executive authority to defer deportation proceedings for young immigrants who entered the U.S. illegally but meet certain requirements was just the latest example of the president's use of his power to act without Congress on policy issues.

And like the other actions the president has increasingly taken as part of his "We Can't Wait" initiative, the decision announced Friday was characterized by Obama's political opponents as an abuse of power and violation of congressional prerogatives.

All of which goes to prove that Obama has reached the stage in his presidency, like so many of his predecessors, where his frustration with congressional inaction has led him to act unilaterally.

William Howell, a political scientist at the University of Chicago who wrote Power Without Persuasion: The Politics Of Direct Presidential Action, said in an interview:

"The boundaries of presidential power are constantly being negotiated and renegotiated. This is very typical. In some ways the option itself may be atypical. We haven't seen presidents issue this particular kind of policy initiative on their own before. But all the time, presidents are pushing out on the boundaries of their power and claiming new authority. And their ability to actually secure that authority crucially depends on how the two other branches of government respond.

"So the idea that presidential power is fixed and static is a deep misnomer. It mischaracterizes both the long trajectory of presidential power over time and it also mischaracterizes what the founders themselves had in mind. They fully expected various branches of government to be pushing and pulling."