Pew reported here:
Asked to choose, nearly half of Muslims in the U.S. (49%) say they think of themselves first as a Muslim, 26% say they think of themselves first as an American, and 18% say they are both. Among U.S. Christians, 46% say they identify as Christian first, while the same number identify as American first.
Ted Cruz, quoted here in January 2016:
In the interview, [former Senate Majority Leader Bob] Dole also said he questioned Cruz’s “allegiance” to the Republican Party.
“I’m a Christian first, American second, conservative third and Republican fourth,” said Cruz, who is currently a distant second place, behind Trump, for the GOP nomination in several national polls. “I’ll tell ya, there are a whole lot of people in this country that feel exactly the same way.”