Sen. Rand Paul (R-Ky.), second from left, watches as Iowa Gov. Terry Branstad cheers on a candidate at the Republican Party headquarters in Urbandale, Iowa, on Wednesday. Paul has traveled 800 miles around the state to support Republican candidates. (Nikki Kahn/The Washington Post)

Ask voters in North Carolina’s Research Triangle what November’s midterm elections are about and one will tell you drones. A second will say closing the prison at Guantanamo Bay, Cuba. Yet another, the middle-class squeeze.

At a Sunday school classroom in Ypsilanti, Mich., voters are concerned about deteriorating roads, teen sex parties, truancy in schools and violent crime. Six hundred miles west at a Republican campaign office in Urbandale, Iowa, people fear that America is on an irreversible decline — like Germany after World War I, as one man predicted.

Across Colorado, voters are thinking about a whole other set of concerns — veterans’ care, driver’s licenses for undocumented immigrants, the soaring cost of housing, the erosion of Christian conservative values, Russia’s rise, and fracking.

This is an election about nothing — and everything. Unlike in previous midterm election years, no dominant national theme has emerged for the 2014 campaign, according to public opinion surveys as well as interviews last week with scores of voters in five key states and with dozens of politicians and party strategists.

Even without a single salient issue, a heavy cloud of economic anxiety and general unease is hanging over the fiercely partisan debate. Listening to voters, you hear a downbeat tone to everything political — the nation’s economy, infrastructure and schools; the crises flaring around the world; the evolving culture wars at home; immigration laws; President Obama and other elected leaders in Washington.

View Graphic No dominant issue leading into midterm elections

“I probably feel the way everyone else feels,” said Lindsay Perry, a 32-year-old Democrat, as she tried to keep her 9-month-old son from tipping over her salad last week at a Durham, N.C., bakery. “Clearly, it’s really dysfunctional and it’s essentially driven by monied interests at this point. It’s really just discouraging. It just seems clear the people’s interests aren’t being represented.”

Over the past 20 years, every midterm election has had a driving theme. In 1994, Newt Gingrich led Republicans to power in a backlash against President Clinton’s domestic agenda. In 1998, it was a rebuke to Republicans for their drive to impeach Clinton. Terrorism motivated voters in 2002, while anger over the Iraq war propelled Democratic gains in 2006. And 2010 turned into an indictment of Obama’s economic stewardship and, for many, his health-care plan.

As long as it has been polling, Gallup has asked voters to state their “most important problem.” For the first midterm cycle since 1998, no single issue registers with more than 20 percent of voters. Immigration was the top concern for 17 percent of those Gallup surveyed in July, while 16 percent said government dissatisfaction and 15 percent the economy.

The result could be an especially unpredictable final 12 weeks of the campaign. With voter turnout expected to be low and several big races virtually tied, campaigns everywhere are searching for pressure points — by taking advantage of news events or colorful and, at times, highly parochial issues — to motivate their base voters to go to the polls.

In Iowa, a neighborhood dispute over chickens wandering into the yard of Rep. Bruce Braley, a Democratic Senate candidate, has become a flap much discussed by Republicans. Democrats in Colorado have zeroed in on Senate candidate and GOP Rep. Cory Gardner’s past support for the personhood movement, which gives fertilized eggs individual rights. Rep. Tom Cotton (R-Ark.), an Iraq veteran locked in a tight race with Sen. Mark Pryor (D-Ark.), has used the recent airstrikes in Iraq as an opportunity to criticize Obama’s “lack of overall Middle East strategy.”

Democrats, who are eager to drive African Americans to the polls, have been sounding the alarm over threats to impeach Obama, even though Republican House leaders insist that is not a real possibility.

“The African American turnout in 2014 will have to be at the level of a presidential year turnout for us to do well,” said Rep. James E. Clyburn (S.C.), the assistant House Democratic leader. “We’ve got to carry a strong message and organize, not agonize, and be ready to take advantage of any opportunities Republicans give us.”

View Graphic Election Lab: See our current forecast for every congressional race in 2014

In talks with voters, there was some evidence that the impeachment issue was resonating with African Americans, though it barely registered more broadly.

The lack of a dominant issue also means that campaigns could be more susceptible than in other years to events this fall. Republicans believe, for instance, that if Obama signs an executive order granting legal status to millions of undocumented immigrants, as White House officials have indicated he might, it will create a huge backlash against Democrats.

And after a summer dominated by problems around the globe — a downed plane in Ukraine, war in the Middle East and the return of U.S. bombs in Iraq — continued trouble abroad could further dampen support for the president and his party.

There is hope in the uncertainty for both parties. Democrats believe they have an opening to use wedge issues, such as same-sex marriage, access to birth control and abortion, to rally opposition against Republicans. Republicans, meanwhile, see the potential to expand their opportunities and turn what they expect to be a good year into a great one.

“It’s like a close basketball game and then something happens, there is a breakaway, and it goes from a three- to four-point game to a 10-point win,” Republican strategist Ed Rollins said.

Senate battle is fierce

The hardest-fought battleground this year is for control of the U.S. Senate. Republicans need to pick up six seats to win back the majority for the first time in eight years.

Republicans are heavily favored to win three elections — in Montana, South Dakota and West Virginia — while another dozen or so races are in play, many in states where Obama is unpopular. Democrats believe they have a shot to pick up seats in Georgia and Kentucky, but red-state victories will be difficult in a year that generally favors Republicans.

Republicans are expected to hold their majority in the House, while a number of incumbent GOP governors are facing stiff challenges from Democrats.

All year, Republicans have tried to make the midterm elections a referendum on Obama’s presidency — specifically, his signature health-care law. In Senate battlegrounds from New Hampshire to Alaska, television ads on Obamacare have been pounding viewers. And some Republican leaders are confidently predicting a wave.

“This is the year,” Iowa Gov. Terry Branstad (R) said. “It’s a midterm election for an unpopular president in his second term. History says that goes against his party. . . . I was on the ballot in 2010, which was a good year for Republicans, and 1994, which was a great year. I think this could be comparable to ’94. I think it’ll be better than 2010.”

But Democrats believe the question that drove voters in 2012 will do so again this fall: Which party is on your side? Democratic candidates are using a more populist pitch than in previous years, touting such proposals as increasing the federal minimum wage to $10.10 an hour and pay equity for women.

“It’s about the fight for working-class and middle-class people contrasted with a fight by Republicans for those at the top,” said Joel Benenson, who served as Obama’s campaign pollster.

The party’s rhetoric about the growing divide between the rich and the poor has become more strident. Even in Republican-leaning states, Sen. Elizabeth Warren (D-Mass.), a liberal who talks tough about Wall Street, has emerged as a popular surrogate this summer.

“There is a lot of angst about whether this country is continuing to provide an opportunity to live the American dream,” former Ohio governor Ted Strickland (D) said. “The overarching concern is an economy that is not providing an opportunity for working people.”

Candidates are grappling with voters’ deeply rooted disgust with politicians and apathy toward affairs in Washington. Republicans are banking on voters placing blame squarely on Obama.

“Look at where the president is at in the polling, look at the history of it, and you can see the malaise,” House Majority Leader Kevin McCarthy (R-Calif.) said. “It’s like when Jimmy Carter told us to put a sweater on and turn the heater down. The president is asking Americans to accept mediocrity.”

But voters don’t see it so clearly. A Washington Post-ABC News poll last week found that 51 percent of all Americans disapprove of the job that their own member of Congress is doing — a record high in a quarter century of Post-ABC polling on this question.

Neil Newhouse, Mitt Romney’s pollster during the 2012 campaign, warned that Republicans should not see the president’s sagging summer poll numbers as evidence of sure disaster for Democrats.

“Republicans made this mistake two years ago when Democrats managed to get voters to the [polls] who were not enthusiastic and lukewarm toward the president,” he said. “Republicans are reading the tea leaves a little too early.”

Gingrich, the former House speaker, said, “I don’t think anybody should underestimate the anger and disillusionment of the American people and how dangerous the environment is.” But, he added, “It’s also not just about Obama. It’s much deeper and bigger than that.”

Consider the television ads two-term Rep. Dan Benishek (R-Mich.) is running in his rural Upper Peninsula district. Benishek, a surgeon, does not state his party affiliation or even mention the fact that he’s a congressman. In his ads, he’s simply “Dr. Dan.”

Nationally, the political conversation on television — fueled by tens of millions of dollars in outside spending by super PACs — has deteriorated with an onslaught of ads.

Democrats in states with rocky political terrain are not only highlighting their independence from Obama, but also focusing on local issues that might help them establish unique brands.

In Louisiana and Alaska, embattled Democratic Sens. Mary Landrieu and Mark Begich are talking about what they have delivered for their poor, rural and — in the case of Alaska — remote states. And in West Virginia, Democratic Senate nominee Natalie Tennant is talking a lot about drug addiction, even holding events devoted entirely to what she calls “our state’s drug crisis.”

“How do you localize it?” Tennant said. “You see so many people have been touched by this, and we need to focus on finding a solution. It’s not a catchy little thing that you hope pulls people out to vote. It’s a situation with real people and real consequences.”

Many issues are in play

The fluid campaign was on display last week as Colorado Gov. John Hickenlooper (D) visited the Aurora Seniors Center, where many voters described themselves as independents and said they are undecided about backing him for reelection. Fittingly, Elvis Presley’s “Suspicious Minds” blasted through a loudspeaker as Hickenlooper worked the room, sounding out the seniors on what bothers them most.

“Russia is coming back,” Lois Doone, 69, said — just like “the old days.”

Bill Reddick, an 84-year-old retired pilot, was focused closer to home. He was upset at Hickenlooper over the lack of political consensus at the state capitol — never mind that the governor said that 424 of his 428 measures and each of his four annual budgets have passed with bipartisan support.

Jerry Barton, an 83-year-old Korean War veteran, fumed about problems at the Veterans Administration. He told Hickenlooper about recently arriving at a VA hospital for an appointment and being told it had been canceled and to return in three months.

Hickenlooper, meanwhile, had an entirely different take on the election. He said the driving issues are housing — costs are “going up like a rocket” — traffic, neighborhood safety and the cost of living.

A world away from suburban Denver, Sen. Mark R. Warner (D) gathered employees of an oil company in rural Southside Virginia for a town hall meeting last week. Warner paced a wood-paneled room fielding questions on immigration, the Export-Import Bank, transportation costs and offshore drilling. A former civil service worker even asked why the government had changed her pension.

And Brian Atwood, 44, a father of two, raised his hand to ask about Vladi­mir Putin.

“A couple years ago in a presidential debate, Governor [Mitt] Romney said Russia was our biggest threat coming up in the future and the president kind of laughed it off and the media kind of laughed it off,” Atwood said.

“I’m on the Intelligence Committee, so I can’t tell you everything,” a smiling Warner replied, winning laughs from the crowd. “Obama isn’t the first president hoodwinked by Putin,” Warner added, offering an impersonation of former President George W. Bush’s comment about looking into Putin’s eyes to get “a sense of his soul.”

Much of the campaign has played out on the airwaves, fueled by nearly $155 million spent by super PACs and other outside groups on TV ads and other campaign expenditures so far this year, according to data compiled by the Center for Responsive Politics, a nonpartisan research group.

A large share of those spots have been focused on the Affordable Care Act. In the first four months of the year, 35 percent of broadcast and national cable TV ads in Senate races took aim at the health-care overhaul, according to data analyzed by the Wesleyan Media Project.

Yet polls suggest relatively few voters have cited their opposition to the law as their animating issue.

“It’s really remarkable that six months ago, it was all about Obamacare,” said William J. Bennett, a former Reagan administration official who hosts a talk show on conservative radio. “Nine out of 10 calls we’d get, if we asked people about their biggest problem, it was Obamacare. Now we can go a week without talking about it on the program.”

In interviews across North Carolina, voters frequently praised the Affordable Care Act. Anna McAllister, a Republican-leaning independent, said the new law has made her reconsider her view of Obama.

McAllister, 20, did not support Obama when she voted for the first time in 2012, but she recently learned that she is able to stay on her parents’ insurance under the law, which came as a big relief as her family already is paying a slew of medical bills for her father, Barry.

“I still don’t think he’s my favorite,” McAllister said of the president, “but it’s helped.”

Nevertheless, discontent with the president suffused nearly every conversation with dozens of voters in North Carolina, which Obama won in 2008 and lost in 2012.

Carmen Cervantes, who immigrated to the United States from Mexico 18 years ago, was initially thrilled when Obama began talking about overhauling the country’s immigration system. Now she’s dismayed by a lack of progress, and she puts most of the blame on the president.

“I voted twice for Obama,” said Cervantes, a 44-year-old nursing assistant from Fuquay-Varina, N.C. “I had a lot of faith in him . . . but it hasn’t happened.”

Immigration status has forced her family to be split apart. She said one of her husband’s brothers was recently deported while his application for residency was pending. “Now the children are growing up here without their father,” she said, speaking in Spanish.

“Immigration is something I think he needs to focus on,” Cervantes added. “I don’t think the president has done anything. I’m not asking him to give amnesty for everyone. But it’s a societal issue and he needs to take action.”

Cervantes, a registered independent, said she is not sure yet how she’ll vote in November.

In Democratic-leaning Ypsilanti, a few dozen people gathered for gospel choir practice at Brown Chapel AME Church voiced disillusionment with Washington. Both parties, they said, have failed to be productive.

“If the people really had their way,” Rev. Jerry Hatter said, “they would vote new people in from top to bottom.”

Rucker reported from Iowa, Costa from Washington and Gold from North Carolina. Wesley Lowery in Michigan, Sebastian Payne in Colorado, Jenna Portnoy in Virginia, and Peyton Craighill and Scott Clement in Washington contributed to this report.