On his Facebook page, Rep. Paul Ryan writes [1]:

Senator Rubio is exactly right on the need to fix our broken immigration system. I support the principles he's outlined: modernization of our immigration laws; stronger security to curb illegal immigration; and respect for the rule of law in addressing the complex challenge of the undocumented population. Our future depends on an immigration system that works.

That's it, but there's a lot in it. Instead of taking the incredibly easy (for me) step of showing how Marco Rubio's amnesty will not work, Ryan signs on to its general "principles".

Is it that Ryan can't figure out what's wrong with plans like Rubio's, or is it that Ryan is too corrupt to care?

Ryan also uses the system is broken canard and implies the secure the border talking point; see both links for more.

Ryan can't use the legally correct term "illegal alien"; he can't even use "illegal immigrant". Instead, he uses the term favored by the far-left: "undocumented". Even the New York Times uses "illegal immigrant", but Ryan can't rise to their level. See immigration terminology for more on the topic.

For more, see Paul Ryan and Marco Rubio. On the general topic of "Mammon Cons" being bad on immigration, see Fiscal Con, libertarians, and Tea Parties. For extensive discussions of why amnesty won't work, see comprehensive immigration reform. For the highly effective alternative to amnesty you won't often hear about, see attrition.

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[1] facebook . com/reppaulryan/posts/103787043132404