Before he acknowledges the other politicians in the audience or launches into his attack on Mitt Romney, Joe Biden usually has a story to tell.

In Green Bay, Wis., it’s about his Catholic school years, when the priests were Packers fans and homeroom always opened in prayer. “At our school, it was ‘in the name of the Father, and the Son, and the Holy Ghost — and Vince Lombardi,’ and it would go from there,” Biden said to laughs.

In York, Pa., he harks back to his family’s roots in Scranton and a love of baseball. In Detroit, he talks about being a union guy.

The everyman pol with the working-class roots and Catholic heritage is at his best with everyday “folks,” as he calls them. The news media has focused on Biden’s gaffes, but as the vice president travels the country, his missteps appear to be less important to the Democratic rank and file than his ability to connect.

It is that strength the former Delaware senator will bring to the Democratic National Convention stage Thursday night, Obama campaign officials said.

Biden has “really helped frame the choice in the campaign,” said Obama campaign manager Jim Messina. “He has an ability to connect and communicate in a clear and effective way. He, like the president, embodies an American success story.”

Biden’s popularity among Democrats is high — nearly eight out of 10 like him, according to a recent Washington Post-ABC News poll. His reviews were mixed among the broader public, with 43 percent holding favorable opinions and an equal number with negative views. Biden is slightly more popular among Americans with incomes under $50,000, with 47 percent rating him favorably.

Biden seems to love his time on the stump, often drawing energetic crowds of 1,000 or more. Over the Labor Day weekend, he traveled to working-class communities in three swing states — Pennsylvania, Wisconsin and Michigan. In York, he used a teleprompter, but Biden likes to make his speeches personal, and he went off script in a shout-out to the state championship high school baseball team.

“I tell you, the other day I said I’d trade the job to be back playing ball again. The press made it like I was being serious, but I’ll tell you what — I might trade it for being state champion!” he said, sounding serious. The crowd spilling out of the warm gymnasium hollered its approval.

Then Biden quickly went for the jugular — pivoting to his prepared remarks. “They call their plan new, bold and gutsy,” he said of the Republican ticket. “But in the neighborhood I come from, there’s nothing gutsy about giving a trillion-dollar new tax cut for millionaires only.”

Biden, who ran twice for president and served in the Senate for 36 years before becoming vice president, has a natural mastery of retail politics, friends said. This year alone, he has spoken at more than 100 political events, including ­speeches, fund­raisers and rallies. The Obama campaign has dispatched him to labor unions and to win over working-class whites as well as to rally Hispanic and African American groups.

At the National Council of La Raza conference, he rolled out the line, “Romney wants you to show your papers, but he won’t show you his.” At the NAACP convention this summer, boos echoed as Biden began to wrap up, because the crowd wanted more.

“He’s always said the first step with trying to help people with their problems is getting people to believe that you understand their problems,” said Ted Kaufman, who served as Biden’s chief of staff for 19 years. “Once he starts talking, people say, ‘He gets it.’ He speaks from his own experience.”

But Biden, who is known for his avuncular personality and shoot-from-the-hip style, is also known for his rhetorical stumbles. In recent weeks, Republicans have painted him as a liability — the Democrats’ “drunk uncle,” according to a Web video released Wednesday by the GOP super PAC American Future Fund. It strings together video of Biden, who doesn’t drink alcohol, saying in Virginia that Obama would win North Carolina, that “jobs” is a three-letter word and referring to this era as the “20th century.”

The attention Republicans are paying Biden, said one of the vice president’s campaign aides, is evidence that, “frankly, he’s getting under their skin and his message is working.”

Biden, who has been careful to stay on his message recently, has laid low in the days before his DNC speech.

When the vice president takes the stage in Charlotte, he will have room to display the skills that have given him a long political life. And there is no sign that he sees this as his last campaign: Biden, who has long wanted to be president, has yet to say whether he will seek the Democratic nomination in 2016.

Felicia Somnez and Scott Clement contributed to this report.