Because the task of a political leader is to do what he believes is better for his country. Sometimes the public opinion is in favor; sometimes the public opinion needs a little bit more time to understand things. ↗
It is the besetting vice of democracies to substitute public opinion for law. This is the usual form in which the masses of men exhibit their tyranny. ↗
Whenever the government of the United States shall break up, it will probably be in consequence of a false direction having been given to public opinion. ↗
The polls are just being used as another tool of voter suppression. The polls are an attempt to not reflect public opinion, but to shape it. Yours. They want to depress the heck out of you. ↗