"We're doing everything we can to provide relief" without going through Congress, Obama said during a campaign stop in Council Bluffs, Iowa.
The department will buy as much as $170 million worth of meat and poultry, $100 million worth of pork products, $50 million worth of chicken and $10 million each worth of lamb and farm-raised catfish, White House press secretary Jay Carney said before Obama's remarks.
"In addition, the president is directing the Department of Defense," Carney said, "to explore ways to encourage its vendors to accelerate purchases of beef, pork and lamb in order to buy more now and freeze it for later."
"We've got a lot of freezers," Obama quipped during his remarks in Council Bluffs.
Farmers and ranchers "depend on good crop season to pay bills and put a roof over heads," Obama said.
The best way to help drought-stricken states is for Congress to pass long-term agriculture reform, Obama said.
"Too many members of Congress are blocking the farm bill from becoming law," Obama said.
He spoke of Rep. Paul Ryan, R-Wis., the announced running mate of presumptive Republican presidential nominee Mitt Romney, saying the House Budget Committee chairman "is one of the leaders of Congress standing in the way."
He urged members of the audience to tell Ryan "if you see him ... to put politics aside when it comes to doing the right thing for rural America and for Iowa."