Answer:
No!
Explanation:
No!
There is a famous example of that. When Harry Truman was seeking reelection, everyone thought he would be defeated -- everyone but Harry Truman.
The poles conducted a telephone pole where they phoned people to ask who they were going to vote for. Thomas Dewey had a commanding lead from people who actually owned a phone, but many poor people didn't. Truman got in by a sound majority (303 to 189 Electorial College -- about 3 million more votes in the popular vote). So if your sample is biased in some way it is doomed not to tell the truth no matter how big it is.