Party leaders erred, he said, by couching the immigration debate in political rather than moral terms. "The argument that it's going to be politically advantageous is not going to be sustainable over time," McKenna said.
Political activists have swapped estimates of how many people now living here illegally might choose to become citizens, register to vote and turn out for Democratic candidates if a path to citizenship is opened. Even the most conservative guesses assume that Democrats would benefit more than Republicans, initially, at least.
Rubio's allies play it down.
"The status quo is not acceptable to Republican voters," said GOP consultant Kevin Madden, who has worked for Romney and others. Republican leaders, he said, must push for the best rewrite of immigration laws they can achieve.
Texas-based GOP consultant Matt Mackowiak noted that evangelical leaders, major business groups and others that opposed immigration changes in 2007 are now on board. He said the Republican Party should focus on attracting Hispanic voters with its standard message of small government and free enterprise, and not worry too much if a new law produces more Democratic-leaning voters for a while.
"If we don't win 40 to 45 percent of Hispanics," Mackowiak said, "we're not going to win elections regardless of whether this happens."
Limbaugh is among those who don't buy it.
"I see polling data again that suggests that 70 percent of the Hispanic population in the country believes that government is the primary source of prosperity," he told Rubio in their recent exchange. "I don't, therefore, understand this contention that Hispanics are conservatives-in-waiting."