U.S. President Barack Obama and Republican challenger Mitt Romney are criss-crossing America two days before the election with campaign stops in several key states where they are virtually tied.

President Obama is starting his Sunday with a morning event in New Hampshire. He then travels south to Florida, before heading northwest to Ohio and ending the day close to midnight in Colorado. On Monday, he returns to Wisconsin and Iowa and holds yet another event in Ohio before heading to his hometown of Chicago, where he will be on election night.

Meanwhile, Mr. Romney is rallying in Iowa before he travels to Ohio, Pennsylvania and Virginia. His agenda for Monday includes a morning stop in Florida before trips back to Virginia, Ohio and New Hampshire. He will spend election night in Boston, Massachusetts.

Polls indicate the two candidates are virtually tied in the key states of Colorado, Florida, Ohio and Virginia. The president holds a slight edge in Ohio and Virginia, while Mr. Romney is ahead in Colorado, and the two candidates are tied in Florida.

The four states are the main so-called “swing states” critical to gaining the 270 electoral votes needed to win the White House.