I don't know all Muslims in America and there aren't enough Muslims in my state to even register as a demographic. But the few I have had this discussion with both locally and on line all do support Sharia law as the way Allah intends the world to be. They do having varying understandings of what Sharia law should be, but all the various interpretations would be unacceptable to non-Muslims.
But the Muslims who classify themselves as peaceful expect this to be accomplished by attrition and attracting people to Islam until it achieves a sufficient majority to make Sharia Law the law of the land. And those who go out of their way to denigrate and ridicule and diminish our JudeoChristian heritage are inadvertently aiding and abetting Islam in that goal. Wherever a vaccum is created, Islam is more than happy to rush in to fill it.
But if we believe in liberty, the Muslims among us are as entitled to believe what they believe as we non-Muslims are entitled to believe what we believe. But Muslims should not be able to act out their beliefs to the detriment of other people's person or property any more than any of the rest of us should be able to do with with impunity.
We have a small but fluctuating Muslim community representing people from a variety of cultural backgrounds that include multi-generational American citizens, immigrants, and foreign students - so what they feel and think varies considerably.
What they feel about Sharia also varies - in particular, how it's interpreted. Many of them feel "sharia" should be the law for practicing Muslims, not for non-Muslims, in the same way that Orthodox Jews follow Jewish law. They apply this to civil matters like marriage, contracts and daily life like Halal and the way they worship. None of the Americans I've talked to feel it should supercede the Constitution. We have a few students from England and Canada that range from fairly secular to fairly observent, none of whom said that Sharia overrules English law or Canadian law.