Republicans want you to think Biden's on drugs at the debate because they've set expectations too low for him

• Republicans regularly portray Joe Biden as feeble and unable to serve as president.
• Ahead of his debate with Trump, they're changing course — even saying he'll be on drugs.
• It's a recognition that they've set expectations too low for Biden, and it could backfire.

Day in and day out, Republicans portray Joe Biden as a man who's too old and enfeebled to carry out the duties of the presidency.