President Obama kicked off a three-day bus tour across Iowa on Monday by announcing that the federal government would buy up to $170 million worth of meat and poultry to aid farmers and ranchers struggling with a devastating drought this summer.

During the announcement, Obama repeated his call for Congress to pass a farm bill that includes short-term relief measures for the drought-stricken agriculture industry. Although the drought is a localized issue, there is vulnerability for Republicans in farm states because the GOP-controlled House failed to pass its own farm bill before the August recess. And Obama criticized Rep. Paul Ryan (Wis.), Republican presidential candidate Mitt Romney’s newly-minted running mate, who opposed the bill.

Iowa is not only heavily dependent on agriculture, but it also has emerged as a critical swing state this election year, with both Obama and Ryan campaigning in the state this week.

“I am told that Governor Romney’s new running mate, Paul Ryan, might be around Iowa the next few days,” Obama told a crowd of about 4,300 at Bayliss Park, an outdoor square in downtown Council Bluffs. “So if you happen to see Congressman Ryan, tell him how important this farm bill is in our rural communities. We’ve got to put politics aside and do the right thing for rural America and for Iowa.”

Monday afternoon, Obama visited the McIntosh family farm in Missouri Valley, Iowa, where he examined dried, brown cornstalks and highlighted his announcement. The family—brothers Dean, Don, Richard and Roger — estimate they’ve lost a third of their crop this year, which is 60 percent corn and 40 percent soybeans. Obama was accompanied by Agriculture Secretary Tom Vilsack.

He said the Department of Agriculture will buy up to $100 million in pork products, $50 million in poultry and $10 million each in lamb and farm-raised catfish. The president also will direct the Department of Defense to encourage its vendors to hasten purchases of meat products. The department buys 95 million pounds of beef and 65 million pounds of pork each year.

The Department of Agriculture provided additional details about the plan Monday, saying the purchases would be used for federal food nutrition assistance programs, including school breakfast and lunch programs, aid for victims of natural disasters and food banks. The purchases are intended to help American livestock producers while providing high quality food to people who benefit from federal nutrition programs.

Hours after Obama’s announcement, Rep. Tom Latham (R-Iowa) said the president should instead pressure Senate Democrats to pass a livestock disaster assistance program approved by the House before the August recess.

“That would do livestock producers a lot more good than a new spending program,” Latham said.

Latham, who is locked in a competitive race with Rep. Leonard Boswell (D-Iowa) to represent the region Obama visited Monday, added that the $170 million in federal assistance would do little to sway agricultural markets. “It’s not necessary,” he said. “Maybe it’s something they can talk about on the campaign trail, but it’s not going to have any affect on the market.”

Obama’s swing will take him to nine cities over three days in a state that holds special memories for him. Not only did Obama’s 2008 campaign catch fire after he overwhelmingly won the Iowa caucuses, but he also won the state with a 9-point margin in the general election against Republican John McCain.

This year, Iowa voters are taking a dimmer view of Obama, with polls showing his popularity having dropped significantly. Among other factors is that Iowa boasts a smaller minority population — a key constituency in other swing states such as Virginia, where Obama is still strong.

Senior Obama adviser David Axelrod said in an interview here that the Obama campaign was already making progress with Iowa voters whose opinions had soured since 2008. And he said that Ryan’s selection as Romney’s running mate only improves the president’s argument for a second term.

“We have a choice of who’s going to stand up for a stronger middle class as a key for bringing the economy back, as opposed to a top-down approach,” Axelrod said. “That’s beginning to really be a center of the debate, and Paul Ryan joining the mix certainly shines an even brighter light on that choice. He’s a guy who has unending faith in the power of tax cuts for the wealthy to cure all our economic ills even when they come at the expense of the middle class.”

Wearing a casual black jacket, Obama arrived at the Council Bluffs appearance in a black tour bus with the presidential seal on the side, which his staff has dubbed “Ground Force One.” Taking the stage under a dreary sky that turned sunny just at the moment he took the lectern, Obama sprinkled his typical stump speech with references to the drought plaguing many farm states this summer, including Iowa.

He also said he would visit the Iowa State Fair later in the day, where he would not ride the bumper cars, as he did five years ago, because the Secret Service will no longer let him. He has also been forbidden, by his wife, Michelle, from having a fried Twinkie, he said.

According to the Obama campaign, the president has visited Iowa 10 times for a total of 12 days since taking office in January 2009. He has visited four times this year.

Staff writer Ed O’Keefe contributed to this report from Des Moines.