Both candidates are courting voters in a series of must-win states and reaching out to a number of voting groups that could determine the election, from working-class white voters in states like Ohio and Wisconsin to Latino voters in Florida and viewers of a popular Spanish-language television network.
Obama and Romney have dueled for an advantage on foreign policy, with attention focused on unrest in the Middle East in reaction to an anti-Muslim video that led to the storming of several U.S. diplomatic posts and the killing of four Americans, including the U.S. ambassador to Libya.
Romney's campaign has pointed to the events in Egypt and Libya as evidence of national security weakness from the Obama administration. Susan Rice, the U.S. ambassador to the United Nations, defended the administration on Sunday talk shows, calling the critique a "very empty and baseless charge of weakness."
Romney and Obama have also tangled over China, each accusing the other of supporting policies that would move American jobs overseas. Romney released a television advertisement last week assailing Obama for "failing American workers" and ignoring unfair trade practices by China. Obama responded with an ad accusing Romney of outsourcing jobs to China when he worked in the private sector.
Obama was kicking off a week of travel in Ohio on Monday, with stops planned in Cincinnati and Columbus. The president was raising campaign cash in New York on Tuesday, followed by events in Florida on Thursday, Virginia on Friday and Wisconsin on Saturday -- all states that Obama carried in the 2008 election. Obama was making his first trip to Wisconsin in months and his most pronounced pitch to voters there since Romney added Wisconsin Rep. Paul Ryan to the ticket. Wisconsin has not voted for a Republican presidential candidate since President Ronald Reagan in 1984 and is considered one of Romney's most enticing electoral targets.
Romney's itinerary included fundraising stops in the Los Angeles area on Monday along with outreach to key Latino voters, including an address to the United States Hispanic Chamber of Commerce and an interview with Spanish-language television network Telemundo. The network interviewed Obama last week.
Romney was also expected to hold fundraising events in Utah and Texas before heading to Florida for fundraisers later in the week.
Both campaigns have competed vigorously for voters in eight states likely to decide the election: Ohio, Florida, Virginia, Iowa, New Hampshire, Colorado, Nevada and North Carolina. The states have dominated the candidates' attention in travel and advertising.
Romney spent several hours Sunday at a Boston-area hotel with advisers, including Ohio Sen. Rob Portman, conducting some preparation for the fall debates and taping an interview with CBS News' "60 Minutes." The first debate, considered a crucial showdown between Romney and Obama, will be held Oct. 3 in Denver.
Romney had planned to hold a rally in Pueblo, Colo., later Sunday, but the event was cancelled after a small aircraft crashed at the Pueblo airport. The event was scheduled to be held at an aircraft museum near the airport. Romney spokesman Rick Gorka said the campaign did not want to interfere with the investigation or any emergency response efforts.
Romney's plane made a short stop in Kansas City, Mo., to refuel before continuing to Los Angeles.