Romney accuses Obama of being weak on Iran. He says the U.S. needs to present a greater military threat.
Attacking Iran is no light matter, however. That is why neither candidate clearly calls for military action.
Tehran can disrupt global fuel supplies, hit U.S. allies in the Gulf or support proxies such as Hezbollah in acts of terrorism. It could also draw the U.S. into an unwanted new war in the Muslim world.
Unions have long been viewed as a way for workers to gain job protections, boost wages and benefits and live a middle-class life. But organized labor has been in a tailspin for decades, losing millions of members and the influence it once wielded in the workplace.
About 14.8 million Americans are members of labor unions. That's just 11.8 percent of the workforce — down from about a third of all workers in the 1950s.
The numbers have dropped as domestic manufacturing jobs go overseas and businesses take a tougher approach against union organizers.
Union leaders want Washington's help in making it easier to organize members and promote the use of union labor. They've had some success under Obama. But Romney says as president, he would reverse all of Obama's union-friendly executive orders. And he'd seek national right-to-work legislation prohibiting unions from collecting dues from nonmembers.
Missile technology is proliferating. It remains unclear how quickly foes like Iran and North Korea could develop a capability to reach the United States with missiles, but the U.S. says Iran is already able to hit allies in Europe.
The United States is spending nearly $10 billion a year on missile defense when military budgets are stretched. But the programs have yet to prove that they can reliably knock long-range missiles out of the sky.
The U.S. is deploying missile interceptors not only on home soil, but in Europe and Asia, drawing complaints from Russia and China. Moscow has said it will resist plans backed by both Obama and Romney. Romney has said he will not compromise with Russia on U.S. missile defense capabilities. And he opposes a missile-defense spending cut favored by Obama.
Supreme Court appointments:
With four justices in their 70s, odds are good that whoever wins in November will fill at least one Supreme Court seat. The next justice could dramatically alter the direction of a court split between conservatives and liberals.
One new face could mean a sea change in how millions get health care, shape gay rights and much more.
Obama already has put his stamp on the court by selecting liberal-leaning Justices Elena Kagan and Sonia Sotomayor, 50-somethings who could serve a quarter-century or more. Romney has promised to name justices in the mold of the court's conservatives.
Since the New Deal, Supreme Court decisions have made huge differences in American lives, from rulings to uphold Social Security, minimum wage laws and other Depression-era reforms to ringing endorsements of equal rights. Big decisions on health care, gun rights and abortion have turned on 5-4 votes.
Unless Congress acts, the trust funds that support Social Security are on pace to run out of money in 2033, triggering an automatic 25 percent cut in benefits that millions of older Americans rely on for most of their income.
That may seem far off. But the sooner Congress acts, the more time to phase in changes slowly.
Social Security could be preserved for generations with modest but politically difficult changes to benefits or taxes, or some of both.
Obama hasn't laid out a detailed plan for addressing Social Security. Romney proposes a gradual increase in the retirement age and, for future beneficiaries, slower growth in benefits for the wealthy.
But nothing will happen without White House leadership.
For millions of retired and disabled workers, Social Security is almost all they have to live on. Monthly retirement benefits are $1,237; average disability benefits, $1,111.