From BigGovernment.com:

Sens. Pat Toomey (R-PA) and Joe Manchin (D-WV) have introduced an amendment to expand background checks for gun purchases. It makes it more difficult for millions of private gun owners to sell their firearms, such as at gun shows.

He also wants every person who buys a gun from a gunshow to go through a background check. How would they be able to implement that without registration?