Mitt Romney has carried West Virginia, South Carolina, Indiana and Kentucky, Fox News projects, while President Obama is the winner in Vermont.
The results put the Republican nominee out to an early lead in the electoral-vote count. Romney has 33 electoral votes to Obama's three; it takes 270 to win. But with dozens of states still voting, the lead will likely swing back and forth throughout the night.
Ohio, where polls closed at 7:30 p.m. ET, is too close to call. Fox News exit polls show Romney and Obama running neck-and-neck in the Buckeye State. The contest is considered critical -- only twice in U.S. history has anyone won the presidency without winning Ohio.
Two other vital battlegrounds where polls have closed, North Carolina and Virginia, are also too close to call. A winner also cannot yet be declared in Georgia.