Tilde expansion vs. variables in Bash

Please, consider the following snippet:

$ export xx=foo
$ sudo bash -c 'echo $xx ~'
/root

Which is ok. We can't see xx. However, if I expose it:

$ sudo -E bash -c 'echo $xx ~'
foo /home/xropi

Though many say *~* is not alias, somehow it's part of the environment because *-E* will expose the original preventing me to defer its evaluation. Is it possible to pass my variables and evaluate ~ as /root in the sudo-ed command? I'd like to get this when running with sudo:

foo /root