Reflecting that intensity, Obama will campaign for 48 hours straight beginning Wednesday through Iowa, Colorado, Nevada, Florida, and Virginia, and then travel to Chicago to cast his ballot early. Along the way, the president will call undecided voters from Air Force One.
Foreign-policy issues have been secondary to domestic economic concerns for most voters, but strategists for both sides know that any misstep or triumph in the 90-minute debate is likely to be magnified in such a tight race and with an expected audience of about 60 million. Romney and the Republicans have sought to put the Obama on the defensive about the administration's policy toward the Middle East.
A new Wall Street Journal/NBC national poll Sunday shows that after trailing Obama all year, Romney is now tied with the president, each with the support of 47 percent of likely voters. The last such poll, taken before the first debate, Oct. 3 in Denver, had Obama ahead, 49 percent to 46 percent.
But Romney dominated a listless Obama in that encounter, and his campaign has had the momentum since then, pulling into the lead in several polls of swing states.
David Axelrod, senior strategist to Obama, brushed off the latest polls during an appearance Sunday on NBC's Meet the Press. He argued that Democrats were turning out in early voting at a higher rate than Republicans.
"I do think this is going to be a very close race, and we've said that consistently," Axelrod said. "We feel good about where we are. We feel we're even or ahead in these battleground states."
The battlefield this year is small, with maybe a dozen states in play. Obama's team is counting on a kind of Midwestern "fire wall" of Ohio, Iowa, and Wisconsin (35 total electoral votes) that would enable it to withstand losses of three states the president carried in 2008: Florida, Virginia, and North Carolina.
Obama's campaign is still actively contesting Florida and Virginia, though Romney appears to have crept into a narrow lead there. When the Romney campaign announced last week that it was shifting staff members from North Carolina, it was effectively declaring victory in the state where Democrats held their convention - a notion that Obama strategists did not dispute.
The Romney team thinks that narrowing polls in states thought to be locks for Obama, including Michigan and Minnesota, could herald openings. And vice presidential nominee Paul Ryan scheduled a stop Saturday in suburban Pittsburgh, leading to speculation that the Republicans may mount a last-minute push in Pennsylvania. Recent polls show Romney within 4 percentage points in the state - which has one million more registered Democrats than Republicans - after months of trailing Obama by double digits.
Foreign policy has been something of a strong suit for Obama. After all, Osama bin Laden was killed on his watch, and the president has ordered more drone strikes against terrorist targets than his predecessor George W. Bush. Obama also ended the war in Iraq and has set a timetable to withdraw U.S. troops from Afghanistan.
And yet Romney and the GOP have criticized Obama's foreign policy, sensing vulnerabilities in his handling of popular uprisings in the Middle East, of Iran's drive to obtain nuclear weapons - and of Israel.
Romney accuses the president of putting "daylight" between the United States and Israel, noting sometimes cool relations between Obama and Prime Minister Benjamin Netanyahu. In particular, Romney has blasted Obama for declining to vow a preemptive strike on Iran's nuclear facilities. (The president says the United States will stand with Israel.)
Billboards in South Florida proclaim "Friends Don't Let Friends Get Nuked," with a graphic of a missile labeled "Iran" flying toward Israel. Another billboard says, "Obama. Oy vey! Had enough?"
Obama may have to answer questions about a report Sunday in the New York Times that the administration had agreed in principle to direct bilateral talks with Iran after the election - which the White House has denied.
The candidates are expected to tangle, as they did in the second debate, about whether the Obama administration was ready for the attack in Benghazi, Libya, that killed the U.S. ambassador and three others.
"We're in arguments over Benghazi, which ought to lead every person to worry about our intelligence capabilities," former House Speaker Newt Gingrich said Sunday on CNN. "If we can't figure out what went on in a relatively open city, in a country we had helped liberate, why do we think we know what's going on with the Iranian nuclear program?"
Former U.N. Ambassador and New Mexico Gov. Bill Richardson said Romney has a "bluster, blunder, cowboy foreign policy."
Contact Thomas Fitzgerald
at 215-854-2718 or email@example.com, or follow on Twitter @tomfitzgerald. Read his blog, "The Big Tent,"