We will all evaluate their product during the debate and amendment process, but they have done good work, and Rubio deserves his fair share of the credit.

My guess is that in the final analysis, Rubio's success as a prospect for the presidency will be judged by answers to these questions: Does Rubio move the Republican base toward a more constructive immigration stand, which will enhance prospects for legislation and Republican standing with Hispanic voters, or does Rubio weaken in the face of the coming onslaught from the recalcitrant wing of the far right?

Does Rubio move the GOP, or does the far right move Rubio?

There are elements of the GOP base, including a number of evangelical groups, that have moved toward moderation on immigration for substantive reasons, while there are other Republicans who have moved toward moderation for political reasons.

Rubio has more political space today than he had before the 2012 election. On the other hand, as economists say, there is a know-nothing wing of rightist Republicans to whom the GOP must say: No. Immigration reform must happen. Real reform.

Will Rubio have the steel to lead an effort that includes saying no to the far right? If he does, will conservative Republicans follow his lead, accept his decision or say no to Rubio?

The second and equally important question is this: Will Rubio have the legislative and political skill to navigate amendments and policy debates leading to passage of a good bill? He may. Remember Rubio was leader of the Florida Legislature. He is a man of legislative experience and skill. The question will be how courageously and cleverly he will use it, and whether or not GOP presidential primary voters, and possibly general election voters, view Rubio's actions on immigration as a major qualification for the presidency.

America urgently needs an immigration bill that becomes law. Almost certainly, as Rubio goes on immigration, so goes the nation. This time I am rooting for Rubio, because a good immigration bill for America is far more important than presidential politics for a campaign that remains three years away. It is Marco RubioMarco RubioMexican politicians have a new piñata: Donald Trump Bush ethics lawyer: Congress must tell Trump not to fire Mueller The private alternative to the National Flood Insurance Program  MORE's moment. May he make the most of it.