Actually MUSLIM American (often originally refugees or immigrants, or first generation of) support Sharia Law in the United States of America. And Jihad too. 

From the findings of the Center for Security Policy’s survey of Muslims in America - *a majority (51%) agreed that “Muslims in America should have the choice of being governed according to shariah.”

And: *Nearly one-fifth of Muslim respondents said that the use of violence in the United States is justified in order to make shariah the law of the land in this country. 

Americans, non-Muslim, do not. 
[...] * broader U.S. population, the overwhelming majority held that shariah should not displace the U.S. Constitution (86% to 2%).

*More than half (51%) of U.S. Muslims polled also believe either that they should have the choice of American or shariah courts, or that they should have their own tribunals to apply shariah.