Fox News Power Rankings: Looking for clues in the polls as we brace for post-debate impact

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Debates are a unique forum in modern politics.

They test a candidate’s knowledge and character. They are seen by tens of millions of viewers. And they cannot be stage-managed by a campaign.

Voters saw all those dynamics at play last Thursday night.

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President Biden was, at times, incoherent.

He spoke in a fatigued, raspy voice, which sources attributed to a cold nearly an hour into the debate.

And he regularly looked stiff or bewildered during his opponent’s answers.

Political analysts and some of the president’s allies said Biden had the "worst debate performance in modern political history."

Others have called for him to step aside (there is no reporting that he will, and that is the only way for him not to become the Democratic nominee).

Flash polls from CNN and Ipsos on Friday called Trump the clear victor of the showdown.

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But it will take longer to assess whether Americans have changed their mind about their vote.

Voters need to hear about and digest the debate, then decide whether it affects their choice. It then takes days for a survey to reach a representative sample of the population. You also want to see multiple reliable polls to adjust for outliers.

A good rule of thumb is