REUTERS/Larry Downing
U.S. President Barack Obama talks about the vote on Capitol Hill on his request to arm and train Syrian rebels in the fight against the Islamic State while in the State Dining Room at the White House in Washington, September 18, 2014.
According to the Washington Post, which spoke to administration officials ahead of the president's address, the executive action will affect about 3.7 million undocumented immigrants who have children who are already citizens or permanent residents, were brought here as minors, or who are highly-skilled workers.
Many Republicans oppose Obama's decision to take executive action, which the White House has said was spurred by congressional inaction on immigration reform.
This post will be continuously updated with details from Obama's speech.