Mitt Romney had a sweeping victory over five Republican primaries, indicating a tight race with Barack Obama in the forthcoming presidential election in November.

Romney won in five northeastern states - Connecticut, Delaware, New York, Pennsylvania and Rhode Island - with 231 delegates in all. The victories moved him closer to the required 1,144 delegates to clinch the official Republican nomination.

"After 43 primaries and caucuses, many long days and more than a few long nights, I can say with confidence, and gratitude, that you have given me a great honor and solemn responsibility," Romney said, setting the tone for a direct challenge to Obama.

The victories in the five states allowed Romney to start his general election campaign. He pointed fingers at the false promises and weak leadership of Obama during his address to supporters in Manchester, New Hampshire.

"Tonight is the start of a new campaign to unite every American who knows in their heart that we can do better. The last few years have been the best that Barack Obama can do, but it's not the best America can do," a jubilant Republican presidential hopeful said in his speech.

"A better America begins tonight," Romney declared.

Focusing entirely on the economic situation in America, the former private equity firm chief deplored the inability of the president to deliver on his campaign pledges of hope and change.

"What do we have to show for three and a half years of President Obama? Is it easier to make ends meet? Is it easier to sell your home or buy a new one? Have you saved what you needed for retirement? Are you making more in your job?," Romney asked an applauding crowd of supporters in New Hampshire.

With the latest victories in Romney's campaign, the Republican presidential nomination looks to be merely an official formality for Romney. There are 14 remaining Republican primaries before the party convention to nominate the presidential candidate in November.

The other two remaining rivals, former House of Representatives Speaker Newt Gingrich and Texas Congressman Ron Paul, are still in the contest. Gingrich has won two primaries so far in the race, South Carolina and Georgia.

With the stage set for a direct fight between Romney and the incumbent Obama, issues such as slow economic growth, housing, education, job growth and health care are likely to be revisited by both sides in coming days.