Pushups won't make Biden campaign strong

Can a candidate who is leading the field by 12 points be weak? That's the question of Joe Biden's run for the Democratic presidential nomination.

The fact is, Biden's campaign is showing signs of weakness. So is the candidate himself. And doing pushups, as Biden suggested he might do to show up President Trump, won't make him any stronger.

In mid-May, Biden led the sprawling Democratic field by 26 points in the RealClearPolitics average of national polls. By late May, the lead was 17 points. By late June, it was 15 points. Today, it is 12.

So Biden's lead is still big, but it's less than half what it was not that long ago.

What might be more concerning to Biden supporters are the signs Biden is not running at full strength, that the 76-year-old former vice president has lost a step.