Romney wins Illinois primary

Romney's decisive win in Illinois Tuesday likely won't help him win Obama's home state in the 6 November election, but it has brought him becoming the Republican candidate in the race for the White House.

He used his victory speech to reprise his attacks on Obama's economic policies and cast the general election as a choice between "economic freedom" and "job-killing regulation."

While Romney may have a better chance of winning over the moderates and independents who often decide general elections, he has failed to rally the Republican party's conservative base in the grueling state-by-state primaries.

Underdog Rick Santorum was unbowed by Romney's widening lead, rallying supporters in his home state of Pennsylvania to help him "close this gap and (move) on to victory!"

His campaign vowed earlier Tuesday to take the fight all the way to the Republican convention in August, but it's not clear if Santorum can stop Romney from winning the 1,144 delegates needed to clinch the deal before then.

Written off in the early days, Santorum, a former Pennsylvania senator, has steadily notched up wins - 10 out of 33 contests - largely with the help of evangelicals and the party's most conservative members.

Prior to the Illinois vote Romney had pocketed 516 delegates, while Santorum had won 236 and former house speaker Newt Gingrich had 141, according to the website Real Clear Politics.

Texas Congressman Ron Paul, a small-government champion, has about 66.

Illinois's 56 delegates will be awarded after final results are officially tallied.

Romney had 46.7% of the vote in Illinois with 99% of precincts reporting late Tuesday, while Santorum had 35%, Paul had 9.3% and Gingrich had 8%.