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SIOUX CITY, Iowa - President Obama received a less than warm welcome and a warning upon arrival at the airport here on the second stop of his Iowa visit, which was aimed at recapturing some of the magic the state gave his run to the White House in 2008.

Greeting Air Force One as it touched down under sunny skies and sultry heat was a hand-painted banner draped across the top of an airplane hangar that reads, "Obama Welcome to SUX - We Did Build This." "SUX" is the airport code for Sioux City.

The message appeared to be a response President Obama's "you didn't build that" remark from a July campaign rally, when he was trying to explain that government - not businesses - constructed public infrastructure on which the economy relies. Republicans have used the four words to attack Obama as out of touch with the realities of owning and operating a small business.

The banner is a reminder that this part of the state remains hotly contested turf for both Obama and his Republican rival Mitt Romney, just as the campaign enters the home stretch.

Sioux City, which sits on the border with Nebraska in the northwest corner of the state, is territory Obama lost in 2008 to Sen. John McCain, even though he won the state overall. Obama won 49 percent of the vote here to McCain's 50 percent, a difference of just 500 votes.

Obama also won the Iowa caucuses, an early confirmation that his message was resonating with Democrats.

This time around, the president's campaign believes it can turn the Sioux City region blue by appealing to middle class values and highlighting the administration's record of tax cuts for small businesses and families.

"We know the President has strong support in Sioux City so it was important to the him to spend time visiting with familiar faces and energizing people at this pivotal time leading up to election day," said Obama campaign spokeswoman Jen Psaki.

Polls show Iowa, which Obama won handily four years ago carrying 54 percent of the vote, is up for grabs in November. Obama and Romney have been locked in a dead heat since early this year.

"Iowa, this is our first stop on the road to our convention in Charlotte, North Carolina. But there was a reason for me to begin the journey right here in Iowa, where it first began more than four years ago," Obama told a crowd of 10,000 in Urbandale, Iowa, earlier in the day.

"Because it was you, Iowa, who kept us going when the pundits were writing us off," he said. "And it will be you, Iowa, who choose the path we take from here."

Psaki said the banner was not visible from the presidential motorcade.

There were no identifying markers on the hangar or the banner to suggest who made it, and a call to the Woodbury County GOP was not immediately returned.

"The people of Iowa are focused on who is going to be a fighter for them in the White House, not on out of context attacks," Psaki said.

The president is on the first of a four-day tour through battleground states, leading up to his formal nomination for the presidency at the Democratic National Convention on Thursday. He spends Sunday rallying supporters in Boulder, Colo.

This post has been updated.