There are some problems with online polling but its proponents point out that the accuracy of online polling when conducted by reputable polling firms compares favorably with traditional telephone polling. Aside from being cheaper online polls can be conducted must faster. That said a recent Bloomberg poll conducted by the polling firm Purple Strategies finds that 65% of Republican primary voters agree with his call to stop the immigration of all Muslims into the US.
If conventional polling bears this finding out it congressional Republicans who condemned Trump owe the voters an apology. In a moral universe they would resign.