(NBCNews) - President Barack Obama on Thursday announced broad executive action to offer temporary relief from deportation to millions of undocumented immigrants, saying that the separation of families or the oppression of low-wage immigrant workers is "not who we are as Americans."

"If you've been in America for more than five years; if you have children who are American citizens or legal residents; if you register, pass a criminal background check, and you're willing to pay your fair share of taxes - you'll be able to apply to stay in this country temporarily, without fear of deportation," he said in a nationally televised address from the East Room of the White House. "You can come out of the shadows and get right with the law."

Obama noted that the move would not grant undocumented immigrants citizenship or the right to remain in the country permanently. And he said that he will still push for a legislative solution - akin to a bipartisan Senate bill passed last year.

" I want to work with both parties to pass a more permanent legislative solution," he said. "And the day I sign that bill into law, the actions I take will no longer be necessary."

Crowds of immigration reform advocates rallied and cheered outside the White House during the address. Republicans, calling the executive order a constitutional overreach that is unfair to legal immigrants, are vowing to fight the executive action.

The most controversial aspect of the president's executive order allows as many as five million undocumented immigrants to stay in the U.S., including the undocumented parents of children born here. Those parents will be able to request deportation relief and work permits for three years at a time, provided that they register, pass background checks, pay fees, and prove that their legal resident or citizen child was born before the date of the executive order.

"Are we a nation that accepts the cruelty of ripping children from their parents' arms? Or are we a nation that values families, and works to keep them together?" he said.

The plan also protects more so-called "DREAMers" -- young immigrants brought to the United States illegally as children. Previously, individuals were eligible for deferred action if they were born after 1981 and entered the country before 2007. That date is expected to change to January 1, 2010, with no age limit.