Referencing a Jay Leno one-liner, Burgess questioned fellow conservatives about the wisdom of giving citizenship to “11 million undocumented Democrats.” Laughter, some of it nervous, spread throughout the room. But not everyone found Burgess’ crack funny. According to several people who attended the June 5th gathering, Rubio glared at Burgess.

This account, confirmed by multiple members and staffers, sheds light on what is perhaps the most politically obvious — and perpetually underplayed — conservative argument against providing citizenship to the nation’s illegal immigrants. With all the noise surrounding the debate over policy specifics — security measures, enforcement triggers, future flow, interior oversight — there is still an underlying political argument whispered among some of Congress’s most conservative members: After 71 percent of Hispanics voted for President Obama in 2012, why should Republicans add millions more to the voting rolls?

Not everyone feels the need to whisper. At this year’s Conservative Political Action Conference, Iowa Rep. Steve King — the leading immigration hardliner in the House GOP — earned laughter and applause during an immigration panel when he quipped: “Even Republicans seem to think that these undocumented Democrats could be made voters and somehow we’re going to win in that equation. And what happens is that two out of every three that would be legalized become Democrats.”