Ryan voted for a $383 million livestock disaster aid bill that the House passed on Aug. 2 before a five-week recess. A Romney campaign spokesman said "no one will work harder to defend farmers and ranchers than the Romney-Ryan ticket."
U.S. farmers are suffering through their worst drought in a half a century as concern mounts that livestock producers can't afford the soaring cost of corn, a staple for feed.
Under the plan announced by Obama, the Agriculture Department will buy pork, lamb, chicken and catfish with money from an emergency fund for responses to natural disasters. The food will be sent to assistance programs, such as food banks.
Obama planned a three-day swing through Iowa, a battleground state the Democrat hopes to win in November. He planned to visit a farm in the No. 1 corn-producing state to witness the impact of the drought. The Iowa corn crop is forecast 25 percent smaller than 2011 due to the worst drought in half a century.
The White House also is directing the Department of Defense to "encourage" its vendors to speed up purchases of lamb, pork and beef and freeze the food for later use.