Romney won with 33 percent of the vote, followed by chief rival Rick Santorum with 29 percent, Texas Congressman Ron Paul with 24 and former House speaker Newt Gingrich with 14, with 86 percent of the state reporting, it said. Romney earlier scored a key win in the closely-fought state of Ohio, and took Virginia, Vermont, Massachusetts and Idaho, while Santorum picked up Tennessee, Oklahoma and North Dakota. Gingrich won his home state of Georgia. Romney failed to secure the knockout punch he had hoped for, virtually guaranteeing the race would continue for weeks or even months, with the candidates vowing to fight on to the Republican National Convention in August. There the party will select a candidate to take on Democratic President Barack Obama in the November 6 general election, in which the slowly recovering US economy is expected to be the central issue on voters minds. Delegates are awarded by each state in the complex Republican Party nominating process, with one candidate needing to reach 1,144 delegates to declare victory. More than 400 delegates were up for grabs on Super Tuesday -- nearly 40 percent of the total needed to secure the nomination. US media projected each of the state results as they came in, but the official vote tally and precise awarding of delegates was not yet known.