Romney wins Super Tuesday in Ohio

Romney and rival Rick Santorum had been neck and neck and at one stage during counting it looked as if Santorum might cause an upset.

With 96% of the vote counted Romney was said to be around 7,000 votes ahead, having previously fallen behind.

Super Tuesday is the busiest day in the Republican race for the White House, with 419 of the 1,144 delegates needed to win the nomination up for grabs.

Romney is also projected to win in Massachusetts - where he used to be governor - and in Virginia, Vermont and Idaho, taking his tally of states to five. 

Santorum was the victor in Oklahoma, Tennessee and North Dakota, while former House speaker Newt Gingrich comfortably topped the poll in his home state of Georgia.

The fourth remaining candidate, Texas congressman Ron Paul, was hoping for his first win in Alaska.