Watch Art Cashin: Why rally could have staying power

Art Cashin says today's strong stock rally is not being driven entirely by short covering, as some on Wall Street have been suggesting. That means the buying could have some staying power.

Cashin, UBS' director of floor operations at the NYSE, talked with CNBC's Bob Pisani around mid-afternoon about the buying sparked when House Speaker John Boehner offered a possible way out of the debt ceiling deadlock.

If it was short covering, Cashin says, you would see a "short, vicious spike and then some pullback. We're really not seeing much pullback here at all which indicates there are still some bids."