President Barack Obama is set to unveil his long-awaited overhaul of U.S. immigration rules -- potentially shielding millions of people from deportation -- Thursday in an 8 p.m. ET speech from the White House.
The impending actions are fraught with political controversy, as Republicans lambast him for circumventing the legislative process to declare "executive amnesty." There's also intense interest surrounding who, exactly, among the nation's 11 million undocumented immigrants will be covered.
Here's our guide on what to watch for during and after Obama's speech tonight:
What would Obama's executive order do?
The centerpiece of Obama's plan is that the undocumented parents of children born in the United States, and therefore citizens, are expected to gain protection from deportation -- potentially benefiting up to 3.5 million people.
It could also broaden protections for undocumented immigrants who entered the country as children, put a new focus on deporting criminals and expand visas for skilled workers. Homeland Security Secretary Jeh Johnson said border security measures will be included, too -- something Republicans have been clamoring for.
Which parents stay and which ones go?
Undocumented parents of U.S. citizen children will be covered. But what about the parents of "Dreamers" -- undocumented immigrants who were brought into the United States as children and have grown up in the country?
Those children themselves got a reprieve from the threat of deportation under Obama's 2012 "Deferred Action for Childhood Arrivals" program. It was a step Obama took after Congress nixed the DREAM Act, which would have given them citizenship, in 2010. Eligibility for the program is also cut off for immigrants who arrived after 2007.
But, despite the Obama administration's position that families shouldn't be split up, administration officials have indicated that Dreamers' parents wouldn't be covered by the president's new action. Obama could address the fate of those parents Thursday night.
Will there be age limits?
Just as the 2010 program only benefited those who arrived after 2007, Obama's latest move could have cut-offs or age limits, too -- and that would narrow the scope of his order.
The Migration Policy Institute estimates that 3.6 million people would be covered if Obama's protections for the undocumented parents of U.S. citizen children comes without restrictions. But that number would drop to 3.3 million if parents are required to live in the United States for at least five years before becoming eligible, and 2.5 million with a 10-year requirement.
How hard will Obama hit Congress?
The President's popularity is battered, but his policy positions on immigration are actually fairly popular. Despite an overall wave of support for GOP candidates, 57% of this year's midterm election voters believe undocumented immigrants should have a chance to apply for legal status, while just 39% want them deported to the country they came from, according to CNN's exit polls from Election Night.
So it will be no surprise when he says that, in his view, Congress should quit whining and start voting on an immigration reform bill if it doesn't like the executive order (One caveat, 48 percent of Americans also don't approve of Obama's executive action on the issue, according to an NBC News/Wall Street Journal poll out Wednesday).
The Senate approved a measure Obama called acceptable in 2013, but the House never gave it a vote. Obama has pointed that out repeatedly in recent weeks as he's moved toward announcing his new action.
But how direct Obama is in his criticism of Congress on Thursday night could reveal just how concerned the White House is about the legal grounds for his move, and the odds that it could be unraveled by an angry, Republican-controlled House and Senate.
How will congressional Republicans react?
Sure, the GOP will decry Obama's move as "executive amnesty" and accuse him of ushering in a bitter new era as Republicans get set to take control of the Senate in addition to the House.
The real question is: What are they going to do about it?
Their first decisions could come quickly, with the government's funding due to expire after Dec. 11. Republicans could try to cut funding in ways that would hamper the Obama administration's efforts to implement his executive order -- though Senate Democrats are all but sure to reject such a move, raising the specter of another government shutdown. Or they could seek a short-term funding measure in order to try again once the GOP takes over both chambers in January.
Two House Republicans who would play a key role in crafting immigration legislation and overseeing its implementation, House Judiciary chairman Rep. Bob Goodlatte (R-Virginia) and Homeland Security Chairman Michael McCaul (R-Texas), fired a warning shot at Obama on Wednesday.
In a letter to the president, they wrote that "as the chairmen of the committees with oversight over border security and our nation's immigration laws, we will be forced to use the tools afforded to Congress by the Constitution to stop your administration from successfully carrying out your plan."
Who will be watching?
Major broadcast networks -- including CBS, ABC, NBC and Fox -- have signaled they will not carry Obama's speech live.
That means much of his audience will be found on cable networks like CNN. And the speech will also occur at the same time that Spanish-language network Univision is airing the Latin Grammies -- with plans to cut away for Obama, giving him access to a crucial audience.
Obama won't be dropping the issue after Thursday night's speech. On Friday he'll talk immigration at Del Sol High School in Las Vegas.