Correction: A previous version of this article misstated the amount of the federal bailout to General Motors and Chrysler in 2009. The auto bailout totaled $85 billion, not $85 million. This version has been corrected.

As Democrats began gathering Monday for their nominating convention in Charlotte, Republican vice presidential nominee Paul Ryan brought the fight directly to them in North Carolina, hitting President Obama hard on the question of whether Americans are better off now than when Obama took office.

“He can’t tell you that you’re better off,” Ryan said at an appearance in Greenville. “Simply put, the Jimmy Carter years look like the good old days compared to where we are now.”

A day after Democratic leaders were mostly mum on the subject — and Maryland’s governor, Democrat Martin O’Malley, even agreed with a questioner that Americans are not better off — the Obama campaign responded aggressively to the attack Monday.

“Folks, let me make something clear — say it to the press,” Vice President Biden said during a campaign stop in Detroit. “America is better off today than they left us when they left. . . . Let me just sum it up this way, folks. . . . Osama bin Laden is dead, and General Motors is alive.”

The newest fight over the national megaphone came as Democrats hoped to pivot the conversation away from Obama’s record during the past four years and pitch it forward instead, making their case in Charlotte that Obama is the right man, and Democrats the right party, for the next four. At a news conference on Monday, the chairman of the Democratic convention, Mayor Antonio Villaraigosa of Los Angeles, said the convention would seek to remind people what kind of economy Obama inherited from President George W. Bush and what would happen if the country went back to the policies put in place by Republicans a decade ago.

Despite recent attention on other issues, both campaigns recognize the dominance of the economy and are battling to gain an advantage as the Democrats convene. The most recent Washington Post-ABC News poll, taken last week, shows that 72 percent of voters say the president’s handling of the economy will be a “major factor” in their vote this November.

Obama continues to get more negative reviews than positive ones for his handling of the economy, and there is tepid confidence that the economy would get back on track in a second Obama term. For more than two years, majorities have disapproved of how Obama is dealing with issue No. 1.

Before a Labor Day crowd of union workers in Toledo earlier Monday, Obama hammered home the argument that the country would have been far worse off if a Republican administration had been in charge during the past four years.

He told 3,000 people at Scott High School here that he “bet on American workers” when his administration provided $85 billion in government loans to GM and Chrysler in 2009. And Obama contrasted his record with that of Mitt Romney, telling the crowd the Republican nominee wanted to “let Detroit go bankrupt.”

“I believed in you,” Obama said. “I bet on you. I’ll make that bet any day of the week. And because of that bet, three years later that bet is paying off for America. The American auto industry has come roaring back.”

Putting his campaign on hold briefly afterward, Obama left the rally in Toledo and flew 21 / 2 hours south to get a briefing from state and local officials in Louisiana and inspect flood damage from Hurricane Isaac. The president had canceled a planned rally in Cleveland to make the detour.

Throughout the day, the Romney campaign tried to counter­program the coming start of the Democratic convention.

Taking the stage four hours away from Charlotte in Greenville, as AC/DC’s “It’s a Long Way to the Top” blared from the speakers, Ryan told a cheering crowd of more than 2,000 at East Carolina University’s student recreation center: “Friends, there’s a little gathering going on over in Charlotte. We know that your governor’s over there, your lieutenant governor. We also know that President Obama’s over there.” Ryan pointed to North Carolina’s 9.6 percent unemployment rate, the fifth-highest in the country, as he argued that Obama “has no record to run on.”

Introducing Ryan in Greenville was GOP gubernatorial nominee Pat McCrory, former mayor of Charlotte. Like Ryan, he argued that Democrats will be playing defense at this week’s convention.

“Can you imagine what they’re going to say in Charlotte?” he asked the crowd. “Are they going to defend Obamacare? Are they going to defend the failed stimulus? Are they going to defend that North Carolina has the fifth-highest unemployment rate in the country?”

Romney spokeswoman Amanda Henneberg, referring to O’Malley’s statement on Sunday, accused the administration of mixing messages: “Vice President Biden claimed that Americans are better off than they were four years ago, directly contradicting what President Obama and his campaign surrogates have said. The truth is that the middle class has been crushed in the Obama economy. Unemployment remains high, incomes have fallen, and gas prices have doubled.”

Republicans plan to continue to press the “Are you better off?” argument during a counter-convention in NASCAR Plaza in Charlotte that will feature daily news conferences, Web videos and high-profile speakers including Sen. Marco Rubio (R-Fla.) and South Carolina Gov. Nikki Haley. The effort, involving more than 50 Republican operatives, is similar to the counterprogramming offered by Democrats in Tampa.

Sunday on CBS, when asked whether Americans are better off than they were four years ago, O’Malley said: “No, but that’s not the question of this election. . . . We are not as well off as we were before George Bush brought us the Bush job losses, the Bush recession, the Bush deficits, the series of desert wars — charged for the first time to credit cards, the national credit card.”

O’Malley adjusted his message Monday during an interview on CNN. “We are clearly better off as a country because we’re now creating jobs rather than losing them,” he said.

On Sunday, David Plouffe, a top Obama adviser, would not give a direct yes-or-no answer to the question of whether Americans are better off than they were four years ago. Monday morning, however, Stephanie Cutter, Obama’s deputy campaign manager, said Americans are “absolutely” better off now.

The auto bailout is central to Obama’s argument. On the trail, he has included the bailout in his stump speech in appeals to Rust Belt voters in states such as Pennsylvania, Michigan and especially Ohio, where the president has appeared 11 times this year. Democrats are expected to showcase the bailout during their convention in Charlotte this week, showing a short film that features remarks from United Auto Workers President Bob King, according to the Detroit News.

But the tableau in Charlotte is complicated by protests from other unions, upset that Democrats chose to have their convention in a right-to-work state that bans ­collective-bargaining agreements that require workers to join unions. Unions have contributed far less money to the convention than in past years, and some workers held an alternative gathering in Philadelphia last month. Some union protests were scheduled for Monday in Charlotte.

Still, labor leaders, including King and AFL-CIO chief Richard Trumka, were on hand to help introduce Obama in Toledo. Last year, Trumka had expressed frustration with Obama for not pushing more strongly for a jobs program, but he grew more supportive after Obama used a Labor Day address last year in Detroit to launch a national tour for a jobs bill in the fall.

Trumka delivered a speech Monday criticizing Romney for trying to pit voters against one another in an effort to win the election. “What Mitt Romney is doing is wrong,” Trumka said. “Those are not the values I grew up with. What he’s doing is beneath the dignity of the American people, and we won’t let him win. There’s something we should do about it. . . . We should support President Obama because he supports us.”

Romney has said Democrats are distorting his position, explaining that he favored a managed bankruptcy and might have offered government aid after such a process was completed.

In a statement Monday, Romney said Labor Day is a chance to “celebrate the strong American work ethic.” But he added that with 23 million Americans unemployed, “today is another day of worrying when their next paycheck will come.”

Obama also visited a Toledo diner to have breakfast with three autoworkers who say the bailout saved their jobs. At the event, Obama recalled his first automobile, a Jeep, as “bright and shiny,” with comfortable seats.

At the high school, Obama was greeted by a crowd that chanted, “Fired up, ready to go!” and “We are the 99 percent!” while awaiting the president.

Obama, in his remarks, obliquely referred to the battle in Wisconsin, where Republican Gov. Scott Walker pushed successfully to limit collective-bargaining rights and then won his recall election after union workers sought to remove him from office.

“When [Republicans] try to pass right-to-work laws, which really mean right-to-work for less and less . . . they hope unions like yours unravel,” the president said.

He also used an extended football metaphor to strike back at Romney’s remark two days ago that the country needs “a new coach.”

Obama said that on first through third downs, Romney would raise taxes on the middle class, roll back financial reforms, and then call a Hail Mary pass by turning Medicare into a voucher system that could raise costs for seniors.

“I have one piece of advice,” Obama said. “Punt it away. It won’t work. It won’t win the game. You don’t need that coach. It’s a losing season.”

Nakamura reported from Toledo. Krissah Thompson in Detroit contributed to this report.