Martha MacCallum challenged White House Press Secretary Josh Earnest this morning on how and why President Obama has reversed course on using executive actions on immigration reform. 

Obama has stated numerous times  in recent years that he does not have the authority to act without Congress to reform the immigration system the way he would like. 

For instance, in May 2011 he said, "Sometimes when I talk to immigration advocates, they wish I could just bypass Congress and change the law myself. But that's now how democracy works."

Despite those previous statements, the president will go ahead with a plan that is expected to grant amnesty to up to 5 million illegal immigrants in a primetime address tonight.

"You've heard all those statements. The question is, what has changed? What has changed the president's mind on this issue so completely," MacCallum asked. 

Earnest responded that there are many other steps the president would like to take, but cannot do through executive actions. He said many of those measures were passed by the Senate in a bipartisan bill last year.

"The president is determined to use all of the authority that he has, that's vested in the presidency, to take the steps that can to try to fix some of the problems that everybody acknowledges exist inside our broken immigration system," said Earnest, arguing that the executive actions are "consistent" with what Ronald Reagan and George H.W. Bush did in the past on immigration.

Martha responded by pointing out that many analysts, including Judge Andrew Napolitano earlier today, have disputed that these sweeping actions can be compared to what was done by Reagan and Bush.

Watch the full interview above and tune in for President Obama's address and comprehensive analysis, tonight at 8p ET on Fox News Channel