The 2010 Republican electoral rout in the industrial Rust Belt was decisive and complete, with the GOP sweeping the gubernatorial and Senate races in the presidential battleground states of Ohio, Pennsylvania and Michigan. In the aftermath, Democratic prospects for 2012, particularly President Obama’s, seemed bleak.

But less than two years later, the dynamics have changed. Things are looking up for the president, and the best evidence may be three Senate Democrats who will head into the final sprint of this year’s campaign as clear favorites, having weathered the worst of the tea party storm in the region.

Their good standing and an improving economy in the area are encouraging for the president, who desperately needs to engage white working-class voters in these must-win states.

Obama is helped by the better-than-average employment picture in Ohio and Pennsylvania, both of which recorded a rate of 7.3 percent in May, while the national level remained at 8.2 percent. Michigan’s unemployment rate in May was 8.5 percent.

The economic instability that continues to threaten Obama’s reelection hopes has not been a vulnerability for Democratic incumbents in these states.

Approval ratings for Sens. Sherrod Brown (Ohio), Robert P. Casey Jr. (Pa.) and Debbie Stabenow (Mich.) have held steady despite continued unease among voters about the pace of the economic recovery and an overall disgust toward Congress, providing some optimism for how Obama can campaign in this critical part of the country.

As he embarked Thursday on a two-day bus tour through Ohio and Pennsylvania, the president had Brown at his side. He will stump with Casey on Friday. The tour, which runs from Toledo to Pittsburgh, presents a stark contrast to the 2010 midterm-election campaigns, when virtually no endangered Democratic incumbent sought the spotlight with Obama.

Some experts think that these Democrats might be able to help shore up the president’s support among wavering party members and swing voters. This is particularly true of Casey, who endorsed Obama early in 2008. The senator has deep support in western, central and northeastern Pennsylvania, areas of uncertainty for the president that have created an opening for Republican challenger Mitt Romney and his party to contemplate an upset in the state.

“Casey will be so far ahead that he can be a messenger to blue-collar voters,” said former Pennsylvania governor Edward G. Rendell (D).

On the bus tour his campaign is calling “Betting on America,” Obama spent his first day emphasizing gains in manufacturing and his administration’s bailout of the U.S. auto industry, hoping to appeal to voters in areas with many union workers. The title is an unsubtle jab at Romney, who has faced questions about offshore personal bank accounts and investments by Bain Capital, made during his time as head of the firm, in companies that eventually outsourced jobs abroad.

“When the American auto industry was on the brink of collapse . . . Governor Romney said we should just let Detroit go bankrupt,” Obama told a crowd of 500 supporters in this manufacturing town just south of Toledo. “I refused to turn my back on communities like this one. . . . And three years later, the American auto industry is coming roaring back.”

The president is paying special attention to Ohio, where he began his 2012 campaign with a speech in Columbus in May and delivered a major address on the economy in Cleveland last month. The Buckeye State has voted for the winning candidate in 10 consecutive presidential elections, and no Republican has won the presidency without capturing Ohio. Consequently, both campaigns are spending much time and ­advertising money in the state.

A Quinnipiac poll released last week gave Obama an edge in Ohio (47 percent to 38 percent) and Pennsylvania (45 percent to 39 percent).

The Romney campaign is not ceding any ground, however, dispatching Louisiana Gov. Bobby Jindal (R) and former Minnesota governor Tim Pawlenty (R) to make appearances along Obama’s bus route to counter the president’s message.

Despite the positive trends for Obama, some political analysts doubt that the popularity of Democratic senators in the Rust Belt will be enough to secure a victory for him, especially if Friday’s employment report shows a third consecutive month of sluggish growth.

“It’s not something that you can transfer from one person to another,” said Mike Dawson, a former GOP adviser to Ohio politicians.

Neil Oxman, Rendell’s former campaign consultant, agreed that it’s going to be difficult for the Democratic Senate candidates to boost Obama, but he suggested that it’s always better to have other popular candidates on the ticket.

In the Senate races, Pennsylvania’s Casey is well ahead of his GOP challenger, coal executive Tom Smith, 49 percent to 32 percent, and Ohio’s Brown has opened up a surprisingly large lead, 50 percent to 34 percent, over state Treasurer Josh Mandel, according to the Quinnipiac survey. In Michigan, according to a recent Epic-MRA poll, Stabenow led her likely opponent, former congressman Peter Hoekstra, by 49 percent to 38 percent.

Mandel remained undaunted, suggesting that Brown’s 38-year history in politics would work against him at a time of Capitol Hill gridlock. In an interview at Tommy’s Family Restaurant near blue-collar Parma, Mandel said Ohio voters want less business and environmental regulation and lower taxes.

“Just vote to repeal Obamacare,” shouted John Lizzini, a Ford electrician from Parma who wore a T-shirt that celebrated “American Classic Muscle Cars.”

The new Republican governors in both states, John Kasich of Ohio and Tom Corbett of Pennsylvania, have endured brutal periods of budget trimming that left them in poor political standing.

Forty percent Ohio voters approve of Kasich’s performance, while 44 percent disapprove; 35 percent of Pennsylvanians approve of Corbett’s performance, while half disapprove. In Michigan, Gov. Rick Snyder’s approval stood at 41 percent.

Although Kasich has faced tough approval ratings since starting a fight with public-sector unions in his first weeks on the job, Corbett’s drop has been more recent and steep. As a former state attorney general, Corbett became the lead public figure in the sexual-abuse case against former Penn State assistant football coach Jerry Sandusky and was viewed as helping usher legendary coach Joe Paterno into exile.

Rendell said he understood the public’s disapproval of the two governors, whose budgets had to be pared down even when their states began to experience job growth ahead of the national average.

“As governor, you make tough choices and you make cuts,” Rendell said.

But the results could reach the president, too. During a lunch stop Thursday at the Kozy Corners diner in the tiny town of Oak Harbor, Obama ordered a cheeseburger, fries and a tall iced tea, taking a seat next to former Ohio governor Ted Strickland (D).

Some diners began chanting, “Four more years,” But Traci Riechman, who works for the Ottawa County Juvenile Court, said she isn’t sure whether Obama will be able to carry the town in November.

“We have a lot of houses for sale,” she said. “It’s just a tough time here in Oak Harbor. I don’t know if the community will be positive or negative.”

Kane reported from Washington. Rachel Weiner in Washington contributed to this report.