Buses, barbecue and big-time politics are the themes for Saturday's Iowa GOP straw poll in Ames, but what actually happens inside Hilton Arena and why is it so important in the Republican presidential race?

"It's the first measurable in the nomination process to find out which candidates have a message that is resonating with Iowa voters in the lead-up to the Iowa caucuses next February," said Matt Strawn, the head of the Iowa GOP. But he admits it's not all serious stuff. "It's county fair meets rock concert meets political convention," he added.

The poll brought in around 14,000 voters in 2007 and organizers expect "tens of thousands" to show up this time around, many of them bused in by the campaigns. It's a big-money event for Ames as the thousands of voters and hundreds of news media members inject nearly $2 million to the local economy.

The struggling overall economy has been the front and center issue as candidates have been criss-crossing the Hawkeye state in recent weeks, making their pitches to potential straw poll voters.

So how will all those voters cast their ballots this weekend and what will it mean to the race for the GOP nomination?

Between 10 a.m. and 4 p.m. Saturday, Iowa voters will render their verdict in what organizers call a "more secure election than state elections." That's because only Iowa residents are allowed to vote in the straw poll, and to make sure that rule is enforced, organizers check voters' IDs before allowing them in the booth. In addition, the votes are cast on board of elections voting machines that are also used in official state and local contests.

However, the official nature of the straw poll ends there. The results are in no way binding. In fact, Democrats don't even have a straw poll, even when they don't have an incumbent president or vice president to re-nominate.

George W. Bush won the straw poll in 1999 and followed up by winning the Iowa caucus, the GOP nomination and the presidency. But he is the only Ames straw poll winner to become president. In 1979, the first time the straw poll was held, his dad, George H.W. Bush, won the poll and the Iowa caucus, but ultimately lost the GOP nomination to Ronald Reagan. Bob Dole won the poll, caucus and GOP nomination in 1995 but lost out to incumbent President Bill Clinton in the general election.

In 2007, Mitt Romney won the Iowa straw poll but lost in the Iowa caucus to Mike Huckabee. John McCain won the GOP nomination after a surprise showing in Romney's backyard at the 2008 New Hampshire primary.

Some analysts suggest the straw poll's third-place finisher could be the real loser. Often a spot for stronger candidates who haven't catapulted to the forefront, the third place finish can be interpreted as meaning that candidate's message isn't working. Previous third place finishers include Sam Brownback, Elizabeth Dole and Pat Buchannan.

The second place spot was kind to Pat Robertson in 1987, giving his campaign a shot of legitimacy, though he ultimately came in third in the race for the nomination.

Still, the Iowa straw poll isn't known for making campaigns and has been known to end them. Some candidates who didn't do so well in the poll have ended their campaigns the next day.

But a strong straw poll finish can carry with it big early momentum. So campaigns who are going all out in Iowa will use buses and barbecue to get their supporters into the political arena in Ames on Saturday in the hopes that while there, they will officially show who's the first unofficial winner in the 2012 campaign.