WASHINGTON  - Newt Gingrich has decided to quit the US presidential race, US media reported Wednesday, paving the way for former Massachusetts governor Mitt Romney to be crowned the Republican nominee. Gingrich, former speaker of the House of Representatives, is expected to hold a final campaign event in Washington on Tuesday May 1, formally ending his White House bid and throwing his support behind his former opponent. “When he says he is transitioning, what he means is that he is trying to determine as a citizen how he will pro-actively help Mitt Romney become president,” CNN reported, quoting its source on condition of anonymity.

A source told Fox News that Gingrich, 68, would “more than likely,” endorse Romney, a multimillionaire businessman and former Massachusetts governor, when he either suspends or ends of his own campaign next week.

And NBC news said on its website that Gingrich would suspend his campaign on Tuesday and could endorse Romney’s bid to oust Democratic President Barack Obama from the White House in the November general election.

Gingrich’s apparent decision to step aside came the morning after Romney, 64, effectively claimed the nomination in a five-state sweep of primary contests.

After wins Tuesday in Connecticut, Delaware, New York, Pennsylvania and Rhode Island, Romney was free to gear up his general election campaign and directly target Obama after months of tangling with Republican rivals.

Gingrich, who after a slow start briefly led polls in the Republican race, pulled off a dramatic win in the South Carolina primary back in January but that victory never produced the national momentum he hoped it would.

On all-important Super Tuesday in March, Gingrich bagged only one of the 10 states on offer, Georgia in his native south, dimming the hopes of his supporters that he might be able to reinvigorate his bid.