"We are dealing with 11 million human beings who are - who are - who are here undocumented, the vast and enormous majority of whom have come here in pursuit of what all of us would recognize as the American dream," he said.
In English, and then in Spanish, he recited his well-known credentials on the subject. "I am clearly new to this issue in terms of the Senate," he said. "I'm not new in terms of my life. I live surrounded by immigrants. My neighbors are immigrants. My family is immigrants. Married into a family of immigrants. I see immigration every single day. I see the good of immigration."
Eight senators agreed on the principles outlined Monday for immigration reform. But while the group was led by Chuck Schumer (D., N.Y.) and John McCain (R., Ariz.), the one who matters most to the success of this effort is Rubio.
Rubio has strong credentials among the tea-party faithful, and he is mentioned as the top presidential choice by some of the most conservative elements of the GOP. His willingness to risk both of these is an admirable act of political bravery.
Republicans, unnerved by the drubbing Mitt Romney received from Latino voters, are moving toward the realization that they've got to drop their no-amnesty absolutism. But the type of voters who dominate the Republican presidential primaries are not necessarily on board with the change.
For Rubio, the safer course would be to keep quiet about his support for what conservatives call amnesty - as Rep. Lamar Smith (R., Texas) did Monday. "By granting amnesty, the Senate proposal actually compounds the problem by encouraging more illegal immigration," he said in a statement. Rubio's refusal to be cowed by Smith will probably get the attention of House Republicans who would otherwise block the Senate plan.
It certainly got the attention of the media. There are seats for 24 in the Senate TV studio, but there were 110 people in the room before the senators and their staffers arrived. No fewer than 21 TV cameras awaited the lawmakers.
Rubio was the last of the senators to talk, following Sen. Bob Menendez (D., N.J.), who delivered a long, grandstanding statement in Spanish. "First of all, let me just say, John, I don't agree with anything he just said about you in Spanish," Rubio joked to McCain. He then made a conservative pitch for a policy that is anathema to many of his fellow conservatives. "We need to be honest with ourselves about how important immigration is for our economy," he said.
When a reporter asked Rubio to elaborate on his support for the new proposal, which goes well beyond his previous immigration efforts, he said, "We have to deal with the people that are here now in a way that's responsible but humane, and this does that."
It's unclear whether Republicans are ready to hear such a message. But Rubio is courageous to try.
Dana Milbank is a Washington Post columnist. E-mail him at email@example.com.