Some say Rubio is trying to get more votes for the bill, others say it's an attempt to maintain conservative support.
Read more...The letter has earned Rubio both criticism and praise from fellow Republicans.
Read more...Marco Rubio doesn't appear to be as optimistic as fellow Gang of Eight members.
Read more...Republicans are letting themselves be held hostage in a way that Democrats would never tolerate.
Read more...The Kentucky senator took Twitter by storm.
Read more...GOP says the plan is missing key steps to reform nation's "broken" immigration system.
Read more...Immigration overhaul is unlikley to win Republicans the Latino vote.
Read more...Still, citizenship could be years away for the undocumented.
Read more...Will Republicans run with new ideas next year?
Read more...Did Paul Ryan really lose in Romney's defeat?
Read more...