Eric Hananoki of Media Matters for America offers "Chicago Tribune falsely claimed Clinton, Obama, and McCain "essentially agree" on immigration" (mediamatters.org/items/200803250002):

Summary: In an article on immigration as a campaign issue, the Chicago Tribune reported that Sens. Hillary Clinton, Barack Obama, and John McCain "essentially agree on the need for an overhaul of U.S. Immigration law that would combine increased border enforcement with a new guest-worker program and measures to permit the estimated 12 million illegal immigrants already in the country to eventually apply for citizenship." In fact, McCain has said he "would not" support his original comprehensive immigration proposal if it came to a vote on the Senate floor and now says that "we've got to secure the borders first."

The article is here. MMFA is just playing word games and confusing support for specific versions of legislation with the fact that all three candidates support amnesty.

McCain now says he wants to "secure the borders" first, but after that (probably largely symbolic move) he'd simply do the same thing as Obama and Clinton would do. All three are supporters of "comprehensive immigration reform", even if what exactly that means changes depending on the tactics they deem necessary to push it through.

3/31 UPDATE: Doubling down, "M.A." (full name unknown) offers '[Lou] Dobbs claimed there "isn't much difference" among the three candidates, except on Iraq' (mediamatters.org/items/200803310008). Note the lawyerly attempt to deceive: "As Media Matters has documented, Obama and Clinton both support comprehensive immigration reform. By contrast, McCain abandoned his previous support for comprehensive immigration legislation during his campaign for the Republican nomination.". He may or may not have abandoned his support for that specific piece of legislation, but not for the overall concept of amnesty.

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Soros-funded Media Matters deletes yet another comment