US Republican presidential candidates were locked in a tight race in the Republican primary where 63 delegates are at stake

US Republican presidential candidates were locked in a tight race in the Republican primary where 63 delegates are at stake.

Mitt Romney's showing in six states was not a super one for the Republican presidential hopeful, who failed to produce the convincing wins needed to demonstrate his ability to generate support among diehard conservatives, CNN reported.

It was best illustrated by Romney's big Super Tuesday win in the bellwether state of Ohio, where he eked out a win over Rick Santorum, after failing to attract strong support from tea party conservatives and evangelical conservatives.

Romney won his home state of Massachusetts as well as Ohio, Idaho, Vermont, Virginia and Alaska, while Santorum took North Dakota, Oklahoma and Tennessee, according to unofficial tallies.

Gingrich grabbed a vital triumph in his home state of Georgia, while Texas Rep. Ron Paul failed to win in any of the states up for grabs.