WRAPUP 4-Romney endorses McCain as Clinton raps Obama

(Updates with Huckabee, paragraph 13)

By Andy Sullivan

BOSTON, Feb 14 (Reuters) - Former Republican presidential hopeful Mitt Romney endorsed erstwhile rival John McCain on Thursday and urged Republicans to unite behind him in a gesture that could help McCain with disgruntled conservatives.

In the Democratic race, Sen. Hillary Clinton scored a much-needed victory in New Mexico and accused surging opponent Barack Obama of lacking substance and experience as she fought for political traction in Ohio after a string of losses.

After a rough campaign battle between them to be the party's nominee in November's election, Romney offered conciliatory words to McCain a week after dropping out of the race, calling him an American hero.

"Even when the contest was close and our disagreements were debated, the caliber of the man was apparent," Romney said with McCain at his side. "This is a man capable of leading our country at a dangerous hour."

McCain said it was a hard campaign but "now we move forward together for the good of our party and our nation."

"We had differences on specific issues, but there was never any doubt about the common philosophy and principles and dedication to the party of Abraham Lincoln, Theodore Roosevelt and Ronald Reagan that we share," he said.

Romney, 61, and McCain, 71, had battled bitterly over who was the real conservative in the race, culminating in a caustic debate in California on Jan. 30.