@Joseph
I challenge what you wrote as the report of Pew Research.
I would expect that Pew Research said that of those American citizens who Identify as Muslim and register to vote….66% are registered with the Democratic Party, 13% are registered with the Republican Party and 20% are unaffiliated.
Here is CT, Independent is the name of a political party that has elected candidates, thus use of the word ‘unaffiliated is important’
There are many Muslims, Jews and Christians in the USA who are not registered for vote.
PEW Research is extrapolated from a sample. It’s reliability in this case is questionable, as your voter registration can not ask your religion. Many respondents to telephone polls lie when answering.