The VP determines what is credible. In the past people in Congress contested, but the VP knew it wasn't credible, and so didn't do anything. Gore knew he lost because of the Supreme Court decision and because he had lost all the recounts. Pence definitely has the power to do something. That's why they gave it to such an important person. Check out recent John Eastman interviews on this if you want to learn more.
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I've heard precinct chairman are also a very important position.