WASHINGTON (Reuters) - Barack Obama is gaining steadily on Hillary Clinton among Democratic superdelegates, nearly erasing her last advantage in a presidential race where those party insiders could be the ultimate kingmakers.

In a danger sign for Clinton, Obama over the past few months has sharply cut her lead among superdelegates -- nearly 800 elected officials and party leaders free to back any candidate.

“Obama has won more delegates, he’s won more votes, he’s raised more money, and now you see it happening with superdelegates too,” said Simon Rosenberg, head of the Democratic advocacy group NDN.

Neither Obama nor Clinton is likely to win enough pledged delegates in state contests to clinch the hard-fought battle for the Democratic presidential nomination, leaving superdelegates to decide the race. The Democratic nominee will face Republican John McCain in the November election.

Despite heavy courting by Clinton, most of the superdelegates who made up their minds since January backed Obama. Clinton’s superdelegate lead dwindled to about 30 from 100 in that time.

A count by MSNBC gives Clinton 256 superdelegates to Obama’s 225. Obama, an Illinois senator, has gained steam in the past month, winning more than two dozen new commitments, compared with a handful for Clinton, a New York senator.

“It has been a drip, drip, drip toward Obama,” said Steven Schier, a political analyst at Carleton College in Minnesota.

“Superdelegates can see Obama’s advantages growing, and it’s pretty clear it’s going to be very hard for Clinton to catch him,” he said. “If Obama notches a few more victories, it could become a stampede.”

Obama has suggested that superdelegates back the candidate with the most pledged delegates -- he leads by about 130 -- and popular votes. He leads Clinton by about 700,000 votes, excluding contests in Florida and Michigan that were not sanctioned by the national party.

Clinton has struggled to overtake Obama in the Democratic contest and has rejected calls from some Obama supporters to get out of the race.

More than 300 superdelegates remain uncommitted or have yet to be named, giving the candidate who wins the bulk of them a path to the nomination.

CLINTON TRIES TO CLOSE GAP

Clinton hopes a strong run in the last 10 contests starting April 22 in Pennsylvania will close the gap with Obama in pledged delegates and popular votes, bolstering her claim she is best suited to beating McCain.

Slideshow ( 12 images )

The private battle for superdelegates has been as tough as the public campaign for votes, with both camps courting uncommitted party leaders and trying to keep supporters in line.

Clinton has suffered high-profile reversals like the decision by U.S. Rep. John Lewis of Georgia, a prominent black supporter, to switch to Obama. Another superdelegate ally, New Jersey Gov. Jon Corzine, suggested that backing a candidate who did not win the popular vote “would be a hard argument to make.”

But she recently won the support of U.S. Rep. John Murtha of Pennsylvania and picked up three more superdelegates this week.

Slideshow ( 12 images )

“Most superdelegates are in a holding pattern. They’re waiting to see what happens in Pennsylvania and down the road before they make any decisions,” Clinton spokesman Phil Singer said.

Rosenberg said the recent string of superdelegate endorsements for Obama made that argument hard to swallow. “A substantial number have moved -- and most are moving to Obama,” he said.

Wayne Holland, chairman of the Utah Democratic Party and a superdelegate, endorsed Obama on Thursday. He said he thought Obama could help Democratic candidates throughout Utah and the West by attracting new voters, donors and volunteers.

“As state chair, my job is to try to elect as many Democrats in various offices in this state as possible,” he said. “I was looking for who could best help us win here, and that was overwhelmingly Senator Obama.”

(Editing by Peter Cooney)