The plain language of the 14th Amendment grants citizenship to anyone born in the United States. At the time the amendment was adopted, the authors understood that doing so would grant citizenship to the children of foreigners. Any attempt to repeal birthright citizenship without actually amending the Constitution would therefore be unconstitutional.
Dave Weigel reports that Rand Paul and David Vitter have figured out a new way around amending the Constitution. They'll just pass a resolution stating that the Constitution says something other than what it says.
Sen. David Vitter, R-La., and Sen. Rand Paul, R-Ken., are jointly introducing a "resolution that would amend the Constitution" -- not an amendment -- to deny citizenship to anyone born in the United States "unless at least one parent is a legal citizen, legal immigrant, active member of the Armed Forces or a naturalized legal citizen."
Is there a word for loving the Constitution so much that you want to pass a law forcing everyone to ignore it? This is basically like forcing the federal government to play a big game of pretend. This game of pretend would have significant effect if it actually passed--it would increase the number of undocumented immigrants in the U.S. from 11 million today to 19 million by 2050, according to a study by the Migration Policy Center.
As with so many attempts to get around the Constitution when it comes to birthright citizenship, this one flies in the face of conservative rhetoric about "original intent." The Founders presumably included Article V of the Constitution in order to make sure it couldn't be changed without an amendment, not so legislators could pass laws agreeing to ignore the parts of the Constitution they don't like.
UPDATE: My mistake, the reason Paul and Vitter are doing this through a joint resolution is that's how you propose amending the Constitution through the Senate rules. So while repealing birthright citizenship remains a bad idea, this is the legit way -- and the only legit way -- to do it.