In the first sentence, I think it would sound unnatural without the "it". Also, since the citizens and the senator are in agreement about the bill, "but" doesn't really fit.
In the second sentence, "it" doesn't really work because "it" should refer to something known, not "a phone". To complement "a phone" you could use "one": “Mary can’t go out without a phone, and I can’t live without one either." The "either" makes the sentence feel more complete to me as a way to connect the topic of these two clauses. (You could also end the sentence with "mine either", although I think "one" sounds more natural here since you didn't say "her phone" in the first clause.)