Because of those stakes, many analysts see Ohio as the pivotal state on election night. No Republican presidential candidate has ever won the White House without also carrying the Midwestern state.
The other five swing states are North Carolina (15), Virginia (13), Iowa (6), Colorado (9), and New Hampshire (4).
The economy is by far the biggest issue in the race. The United States has struggled to return to full strength after the late 2008 financial meltdown and the Great Recession, which began during Bush's presidency. Obama takes credit for preventing deeper problems and says that the economy, while not ideal, is on the road to recovery and that Romney would reinstate the policies that led to the collapse. Romney says the continued economic weakness demonstrates the failure of Obama's policies and, noting his own record as a successful businessman, says he knows how to stimulate the private sector and create jobs.
Polls show that nationwide, Romney holds a slight lead as the candidate best qualified to handle the economy. Nevertheless, Obama maintains his edge in Ohio, where his decision to lend federal money to the failing auto industry saved thousands of jobs.
Other major issues include the huge federal deficit, health care and immigration. Those may be especially important in Florida. The state has a large Hispanic population, and Obama is far more popular with that voting bloc generally — not counting the traditionally Republican-leaning Cuban immigrant community. Romney's tough stance on illegal immigrants could hurt him with Hispanics.
Florida is also a haven for retired Americans who rely heavily on Social Security, the federal government pension system and Medicare, the government-run health system for people 65 and over. Some older voters might fear that the deficit-cutting proposals of Romney and his vice presidential running mate, Rep. Paul Ryan, could lead to reduced benefits.
Florida was ravaged by the recession, with high unemployment and a collapse of the real estate market. That economic suffering would seem to argue in Romney's favor.
International issues are unlikely to sway many voters. Obama has pointed to his efforts against terrorism, including authorizing the military operation in Pakistan that killed terrorist leader Osama bin Laden, and the administration's withdrawal of U.S. forces from Iraq. Romney says Obama has been weak with U.S. adversaries like Iran and unsupportive of allies like Israel. Romney has also promised to crack down on what he sees as unfair trade practices by China.
Obama is America's first black president and Romney would be its first Mormon president, but neither race nor religion has been widely discussed in the campaign.
Money spent on the 2012 presidential campaign has passed the $2 billion mark.
A big reason for the increase this year was the 2010 Supreme Court ruling in the Citizens United case that allowed corporations and unions to spend unlimited amounts in political campaigns. The ruling reversed a century of U.S. precedent that limited financial involvement by those organizations.
Figures compiled so far show Obama had easily outraised Romney personally, but the president was being vastly outspent by outside sources backing the Republican challenger.
While attention has focused on the White House race, control of Congress is also at stake. Republicans are expected to retain their House majority. Democrats had been considered in danger of losing their Senate majority, but analysts now predict they will hold it by the narrowest of margins.
A third of the 100-seat Senate will be at stake. To win a majority, Republicans need a net pickup of four seats if Obama is re-elected, or three if Romney prevails (the vice president casts a tie-breaking vote). The retirement of some Democratic senators in conservative-leaning states seemed to open the door for Republican gains. But in several states, Republicans who emerged from the nominating primaries were candidates who, while appealing to the party base, are seen as potentially too conservative or otherwise undesirable for mainstream voters.