CHARLOTTE, N.C. — Do you ever wonder what each person in the human backdrop at a political rally is thinking? The 60 or so workers sitting in rows behind Florida GOP Sen. Marco Rubioand in front of a giant American flag at SteelFab, Inc. in Charlotte on Wednesday were especially hard to read. Almost half of them wore shades and occasionally chuckled to themselves and each other. On cue, they applauded and held the Romney campaign signs that had been handed out.

Sen. Marco Rubio (R-Fla.) (J. Scott Applewhite/AP)

Coming from a fund-raiser for conservative U.S. congressional candidate Robert Pittenger, Rubio made sure to acknowledge the men on stage, looking back to joke, “Didn’t they give you guys the day off?” before he turned his attention out front. Later in his speech, he was dead serious when he called them the hard workers that make America great.

It was the kind of scene you’ll see more of in North Carolina, an important swing state that Mitt Romney needs and President Obama wants. Considering polls that take turns favoring one candidate, then the other and Obama’s 2008 narrow victory in the state, turnout is crucial. Events like this one excite the base. A line-up of GOP candidates in other state races gave brief pep talks; a voter registration table out front was a reminder that early voting starts here on Oct. 18.

Rubio revved up the crowd with references to the Declaration of Independence, the free-enterprise system and the idea that rights “don’t come from government, our rights come from God.” To applause, Rubio said, “If you have a good idea, you have a God-given right to take it as far as your work will take it.” And though a few of the several hundred gathered – a mix of GOP faithful and plant employees — loudly disagreed when Rubio said Obama wasn’t “a bad person,” everyone loved his denunciation of “out of control” regulations and the need for “enough votes in Congress to repeal Obamacare and a president who would sign it.”

After the speech, I caught up with Shelton Camp, a welder who had been sitting just behind Rubio. He was there, he said, supporting his company and his boss, CEO Ron Sherrill, who had introduced Rubio. Sherrill had told the plant workers their opinions were their own, Camp said. The 37-year-old from Gastonia, N.C., said he liked Obama’s affordable care plan because it had allowed his temporarily unemployed, college-educated brother to get insurance. “He’s had some health problems.”

Corey Hudson, 33, didn’t know much about Rubio, but chose to sit on the sidelines and enjoy his break from work. “I’m a Democrat,” he said, because he’s “against making the poor poorer and the rich richer.”

But there were plenty of true believers in the crowd. Michelle McCall, a social worker from Charlotte, reacted as soon as Rubio took the stage. “Whoa! Awesome!” she said. “He’s so young!” When Rubio finished recounting his own family story — from Cuba to America – by stating his party “never believed the only way to climb up the economic ladder is to pull someone down,” McCall responded, “well said,” out loud and to no one in particular.

McCall, who wore a Mitt Romney for president pin, has held fundraisers for Republican candidates in her home. Though she disagrees with the GOP party plank on abortion – “that’s a personal choice between a woman and her doctor” – she said, “No candidate is going to be perfect.”

Jo Lynn Stern and her husband, John Stern, who have attended tea party rallies in Washington, came from Belmont, N.C., to see Rubio. “I’ve been impressed with him; he’s a rising star,” she said. “He effectively communicates conservative principles and values.” Mitt Romney? “He’s a solid candidate; he doesn’t have the charisma that a Marco Rubio has or a Paul Ryan has.”

John Stern said he admired Rubio’s suggestions for compromise on the immigration issue. “Both sides have to be in the middle,” he said. “We’re not going to deport everybody.” Growing up in a diverse neighborhood in New York, he said everyone was equal, though they didn’t all have the same opportunities. He would like to see more African Americans in the GOP, but blamed the “problem” on “the black establishment that demonizes any black person who’s a Republican,” giving Clarence Thomas and Ward Connerly as examples of those who have been criticized.

Camp, an African American, said he’s still trying to figure this election out. The welder who had been unreadable during the rally told me he had only voted one time in his life and may not vote this year. That was when N.C. Republican Party chair and former congressman Robin Hayes interrupted our conversation. When I had asked Camp if he had volunteered to sit on the stage, what was his answer, Hayes wanted to know. You told her yes, right? Hayes prompted. “Sure,” said Camp.

Republicans in North Carolina aren’t taking any chances.

Mary C. Curtis, an award-winning multimedia journalist in Charlotte, N.C., has worked at The New York Times, Charlotte Observer and as national correspondent for Politics Daily. Follow her on Twitter: @mcurtisnc3