Since trading barbs with Sen. Marco Rubio in Tuesday's Republican debate, Sen. Ted Cruz has struggled to explain why he introduced an amendment to the Senate "Gang of Eight's" 2013 comprehensive immigration bill.

Normally senators introduce amendments to improve bills and subsequently vote for them. Yet Cruz insists he never had any intention of voting for the legislation. He is now labeling his amendment to block citizenship for 12 million illegal immigrants in the U.S. a "poison pill" that would have nullified the plans of the bill's sponsors, including Rubio, to retroactively legalize millions of residents.

The junior senator from Texas told Fox News' Greta van Susteren he introduced the amendment as part of a larger strategy to at least thwart the bill's goal of legalizing "undocumented Democrats" in the next election. Cruz made his argument in a lengthy interview that aired Friday night.

"This was a fight to defeat the Gang of Eight and we called their bluff by introducing this amendment. I said, well gosh, if you say it's not about citizenship, then let's take citizenship off the table," Cruz said, adding that even Democratic Sen. Chuck Schumer knew it was a poison pill to override the bill's legalization language.

Read more on WashingtonExaminer.com