Yeah, not so much anymore.

As a coalition of Republican business executives, prominent conservatives and evangelical leaders kick off a new campaign urging the GOP to take-up immigration reform, Sen. Marco Rubio (R-FL) — the most prominent Republican senator to support an overhaul of the immigration system — formally walked away from his own immigration bill. A spokesperson for the senator said on Saturday that Rubio opposes conferencing a piecemeal House-passed bill with the Senate’s proposal in order to produce a comprehensive measure that both chambers could support.

This is the kind of shit you never walk away from in politics. Rubio may have perfectly good reasons for abandoning a bill, but in debates and in political ads, he'll always be the guy who wrote a bill and then backed off on it. It's not the end of Rubio's career in the Senate, but it's certainly not the kind of behavior that people, especially Republicans, want to see in their presidents.