The campaign of one of the most colourful contenders in the Republican presidential nominee race looks likely to come to an end this week with a spokesman for the former House of Representatives Speaker, Newt Gingrich, announcing that Mr. Gingrich will step down and back the leader in the race, Mitt Romney.

Mr. Gingrich's decision to quit the race comes on the heels of a dramatic sweep of five States by Mr. Romney on Tuesday, including resounding victories in New York, Connecticut, Rhode Island, Pennsylvania and Delaware. According to reports, Mr. Romney boasted more than 50 per cent of the vote in all five States.

On Wednesday, during a campaign stop in North Carolina, Mr. Gingrich said: “I do think it's pretty clear that Governor Romney is ultimately going to be the nominee, and we'll do everything that we can to make sure that he is, in fact, effective.”

Over the last year, Mr. Gingrich sometimes struggled to keep up with a highly variegated cast of challengers in the fight for the nomination but won over audiences with his fiery oratory during the Republican presidential debates and went on to enjoy a surge in popularity.

He became particularly known for his stout rebuttals whenever his rivals or media questioned his family values on the grounds that he allegedly had several affairs culminating in his third marriage.

As the gruelling season of primaries, which began in January, plodded on into late spring, Mr. Gingrich found himself trailing not only the former Governor of Massachusetts but also Rick Santorum, the ultra-conservative former Senator from Pennsylvania.

After Mr. Santorum bowed out of the race for personal reasons, the gap between Mr. Romney and Mr. Gingrich in the delegate count — the all-important variable in deciding the nomination — continued to grow.

As it stands Mr. Romney has cornered 844 delegates, Mr. Santorum held 260 delegates, Mr. Gingrich is in third place with 137 delegates and libertarian candidate Ron Paul trails the pack with 79 delegates.

With 1,144 delegates required to secure the nomination in Florida in August, Mr. Romney has all but been anointed the ultimate challenger to President Barack Obama in the November election.

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