Correction: This article has been corrected to reflect that Rep. Paul Ryan (R-Wis.), and not Vice President Biden (D), has headlined the most campaign events in the weeks following the Republican and Democratic national conventions.

Vice President Biden’s off-script remark at a campaign rally Tuesday that the middle class has “been buried for the last four years” has rekindled debate over his effectiveness on the stump, with defenders contending that such gaffes are a sign of Biden’s authenticity, while critics argue that he has served as more of a punch line than an effective messenger on the trail.

With the vice presidential debate just a little more than a week away, Republicans have begun ramping up their criticism of the No. 2 Democrat, noting that whereas Biden as a senator was a regular on the Sunday talk-show circuit, Biden the vice president has not sat for a national TV interview since the “Meet the Press” appearance in which he — apparently unintentionally — preempted President Obama in expressing support for same-sex marriage.

That appearance came five months ago — a point not lost on some of Biden’s detractors, some of whom contend that in addition to being gaffe-prone, the vice president sits down for interviews so infrequently he must be part of “an Obama-campaign-designed Witness Protection Program.”

“Thank you, Vice President Biden — for the first time in a long, long time, you’re right,” former New Hampshire governor and top Romney surrogate John H. Sununu quipped of Biden’s remark on a conference call with reporters Tuesday afternoon.

The vice president’s defenders see things differently. They contend that the occasional slip of the tongue is to be expected from a candidate as candid and unscripted as Biden. They point to the vice president’s busy schedule on the trail — he has held more than 100 campaign events this year alone, many in a host of battleground states — as proof that he is an asset to the Democratic ticket.

And they argue that Biden is spending his time doing what matters most — speaking directly to voters, particularly those in the middle class — at rallies as well as at his frequent stops at diners, school sports practices and local food stands.

At those informal events, they contend, Biden is accessible to the public and members of the news media alike, giving the vice president greater exposure than in TV interviews alone.

“They usually don’t go after you unless you’re landing punches, and this is about attempting to go after him in a way because he’s such an effective communicator for the middle class,” said Biden’s son, Delaware Attorney General Beau Biden (D).

“What matters here is two basic things: One is an understanding of the middle class, which my father knows and has lived and which Gov. Romney never will understand,” he added. “And Romney’s underlying policies will hurt the middle class, because they’re the same policies that got us into the mess that the president inherited. Everyone in that venue knew.”

The vice president’s “buried” comment, made at a rally in Charlotte, N.C., triggered an immediate onslaught of criticism from Republicans up and down the ballot.

Republican presidential nominee Mitt Romney tweeted that “the middle class has been buried the last 4 years, which is why we need a change in November.” His running mate, Rep. Paul Ryan (Wis.), opened his remarks at a rally in Burlington, Iowa, by telling the crowd “we need to stop digging by electing Mitt Romney as the next president of the United States.”

And at an evening news conference in Colorado organized by the Romney campaign, freshman Rep. Cory Gardner (R-Colo.) called the comment a “significant setback” for Obama on the eve of the first presidential debate.

On Wednesday, the GOP focus on the remark stretched on for a second day, as the Romney campaign announced that it was selling an “Honest Joe” T-shirt featuring Biden’s “buried” comment, and Sen. Marco Rubio (R-Fla.) told a crowd in Denver that Biden is “the best thing” the Republican Party has going for it.

The episode has also brought about fresh scrutiny of how Biden is deployed by the Obama campaign on the trail.

Biden has held no fundraisers for the Democratic ticket since the end of both national party conventions. In that same period, Romney has headlined 22 fundraisers, Ryan has held 16 and Obama has held nine, according to a Washington Post tally.

What Biden has done is headline more than two dozen campaign events in battleground states since the end of the Democratic and Republican conventions, making him second only to Ryan in terms of the number of events he has held in recent weeks.

A look at the areas to which Biden has been dispatched provides some insight into the ways in which the Obama campaign views him as playing an effective role on the trail, particularly when it comes to stumping in less-than-friendly territory for Democrats.

Of the 25 campaign events in battleground states that Biden has held since Sept. 6, 17 have been in counties that Obama won in 2008, while eight have been in counties won by Sen. John McCain (R-Ariz.), according to a Washington Post analysis. Going back to results from eight years ago, the field tilts even more toward the GOP: 13 of the 25 counties were won by George W. Bush in 2004 while 12 went for Sen. John Kerry (D-Mass.).

Those GOP-leaning areas of battleground states Biden has visited in recent weeks include parts of eastern and southern Ohio, as well as Chesterfield, Va., and Ft. Myers, Fla.

Obama, by contrast, has done 24 events in the same time span, 21 of which were in counties he won in 2008. All but one of those 21 were counties where he won by a margin of five percentage points or greater — places such as Clark County, Nev., and Franklin County, Ohio, which he won by 18- and 19-point margins, respectively, over McCain.

Taking the 2004 results into consideration, Obama is still campaigning on decidedly more Democratic-leaning turf than Biden: 14 of the 24 events were held in Kerry counties, while 10 were won by Bush.

Ted Kaufman, the longtime Biden chief of staff who was appointed caretaker of his former boss’s Senate seat after the 2008 election, argued that Biden is similar to former president Bill Clinton in that they both have an ability to communicate to voters “not just issues and things like that, but communicate that they feel their pain” — a skill that helps both men serve as a ‘universal campaigner.’”

“People almost instantly realize they may not agree with him, but he understands their problems,” Kaufman said of Biden. “And whether he’s working the rope line, or whether he’s working a bigger group or doing a television thing, one of the things that comes across with the people listening to him is, ‘This guy, he knows what it’s like to go through tough times.’ ”

“And this year especially, there’s a lot of people who’re going through tough times,” Kaufman said.

In an interview with The Washington Post ahead of the Democratic National Convention, Obama campaign manager Jim Messina described Biden as a candidate who has “really helped frame the choice in the campaign.”

“He has an ability to connect and communicate in a clear and effective way,” Messina said. “He, like the president, embodies an American success story.”

Beau Biden echoed that view of his father, telling a story of how — even at a moment when he is occupied with debate preparations — the elder Biden last Saturday night offered to babysit his grandchildren at his Wilmington, Del., home so that Beau and his wife could attend a wedding.

“In the midst of focusing so methodically for the debates, he focused on that thing that is so important — being a good grandfather, a good father, a good spouse,” Beau Biden said. “And in between it all, he was coming out of the laundry room with a bunch of clothes in his hands. . . . That’s what the American people are doing. They’re trying to make it all work. And you know, it’s not always easy to make it all work.”

He added: “This is someone who has not forgotten who raised him, where he was raised, in Scranton and Wilmington.”

Whether or not that part of Biden’s political persona ultimately becomes overshadowed by his frequent misstatements is likely to have ramifications both for the 2012 campaign as well as for his future beyond November. Biden has declined to say whether he plans to pursue a White House bid of his own in 2016, although those close to him maintain that any discussion of a presidential run is premature.

“The rule in our house is there’s one date that we have in mind, and that is Nov. 6, so there’s no discussion in this house about anything other than Nov. 6,” Beau Biden said.

Asked whether he believes Biden has shut the door on a future political bid, Sen. Tom Harkin (D-Iowa), who has known the Delaware Democrat for nearly 30 years, responded, “No, I don’t think the door is shut at all.”

“That’s just something that’s going to have to sort itself out sometime in the future,” Harkin said. “Joe has been very effective. . . . What he wants to do in the future, he’ll have to decide at some point down the road. But I wouldn’t count him out of anything.”

Krissah Thompson contributed to this report.