Santorum wins North Dakota Republican caucuses

Rick Santorum has won North Dakota's Republican presidential caucuses, adding to his wins in Tennessee and Oklahoma.

Rick Santorum has won North Dakota's Republican presidential caucuses, adding to his wins in Tennessee and Oklahoma.

Rival Mitt Romney has also won three state contests in Massachusetts, Virginia and Vermont. Earlier, Newt Gingrich won the Republican contest in his home state of Georgia.

Santorum and Romney are battling in a close race for the Midwestern industrial state of Ohio. With 66% of Ohio's precincts reporting, Santorum has 38% and Romney has 36%.

Republican-presidential-candidate-former-Pennsylvania-senator-Rick-Santorum-right-celebrates-with-his-wife-Karen-at-his-election-night-rally-at-Steubenville-High-School-in-Ohio-AP-Eric-Gay

A total of 10 states are voting on Super Tuesday.

More than 400 delegates were at stake on the busiest day by far of the race to pick an opponent to President Barack Obama in the November election.