(CNN) -- Despite an overwhelming defeat in North Carolina and a narrow victory in Indiana, Sen. Hillary Clinton vowed to stay in the race until her party has a nominee.

"I, obviously, am going to work as hard as I can to become that nominee. That is what I've done; that's what I'm continuing to do," she said Wednesday in Shepherdstown, West Virginia.

The focus of the Democratic race now turns to the superdelegates, because they outnumber the remaining pledged delegates.

Neither Sen. Barack Obama nor Clinton is expected to win the 2,025 delegates needed to capture the nomination during the remaining contests. That means the superdelegates -- party and elected officials who are allowed to vote during the national convention -- will probably decide who becomes the nominee.

Obama is ahead of Clinton in total delegates: 1,842 to 1,686. Watch how the numbers work against Clinton »

Clinton narrowly leads Obama in superdelegates who have publicized whom they are voting for. But the superdelegates are beginning to head to Obama's corner, said David Gergen, a CNN political analyst. "The superdelegates are starting to move. The dam is breaking," Gergen said. "No matter what happens in these primaries, it's much less important than the fact that the superdelegates are starting to swing his way, and that, in turn, will try to put pressure on her."

'The Situation Room' Sen. Barack Obama talks to Wolf Blitzer on CNN's "The Situation Room."

Today, 4 p.m. ET see full schedule »

Obama's campaign announced four new superdelegates for the Illinois senator on Wednesday, compared with one coming out for Clinton.

Only 217 pledged delegates are up for grabs in the remaining six contests: West Virginia, Kentucky, Oregon, Puerto Rico, Montana and South Dakota.

Obama chief strategist David Axelrod said that during the six contests remaining, his candidate and Clinton will "probably end up roughly splitting the remaining delegates."

"There's more superdelegates uncommitted right now than there are remaining pledged delegates," Axelrod noted. "We feel by May 20, we will have secured a majority of the delegates. So, I think we're in a very strong position here."

Clinton met with Democratic Party officials on Wednesday and undecided members of Congress on Tuesday afternoon to make her case for the nomination and press for a resolution to seating the delegations of Florida and Michigan.

Meanwhile, House Speaker Nancy Pelosi said the race was not over.

She has repeatedly said she remains neutral in the Democrats' nomination battle but said Clinton's slim margin of victory in Indiana doesn't mean her campaign was finished.

"A win is a win. Let's just call it what it is," Pelosi said, adding that a protracted Democratic fight for the nomination isn't going to hurt the party.

"I believe the races must continue," she said. "The people should all have the opportunity to speak as long as two candidates wish to compete in those primaries and caucuses. In a few weeks, we will be on our way to nominating the next president of the United States."

Clinton needs to convince superdelegates that she'd be a better matchup against Sen. John McCain, the presumptive GOP nominee. Watch Clinton vow to fight on »

"I believe that I'm the stronger candidate against Sen. McCain, and I believe I would be the best president among the three of us running. So, we will continue to contest these elections and move forward," she said Wednesday.

Sen. Dianne Feinstein, a key supporter of Clinton's White House bid, said Wednesday that the drawn-out race for the Democratic presidential nomination is producing "negative dividends in terms of strife within the party."

Feinstein, D-California, said she wants to talk to Clinton to "see what her view is on the rest of the race, what the strategy is."

Obama pulled out a 14-point win in North Carolina on Tuesday, and Clinton barely took Indiana, winning by 2 points.

Tuesday was Clinton's last major opportunity to significantly cut into Obama's lead in the delegate count. The 187 delegates at stake were awarded proportionally, meaning Obama padded his lead while Clinton slipped further behind.

In Obama's speech Tuesday night, he looked ahead to the general election, mentioning Clinton only to congratulate her on Indiana and avoiding all talk of recent campaign controversies.

Obama disagreed with the idea that his party is "inalterably divided." Watch Obama call for party unity after winning North Carolina »

"This fall we intend to march forward as one Democratic Party, united by a common vision for this country. Because we all agree that at this defining moment in history -- a moment when we're facing two wars, an economy in turmoil, a planet in peril -- we can't afford to give John McCain the chance to serve out George Bush's third term. We need change in America," he said.

The New York senator's campaign is staying optimistic, despite countless headlines that have all but crowned Obama the nominee.

Her senior campaign advisers insisted Wednesday that her loss in North Carolina, a razor-thin victory in Indiana and the revelation she had lent her campaign another $6 million over the past month -- for a total of more than $11 million since the primary season began --­ all represented positive developments for her White House run.

Contrast that to Pennsylvania, when the campaign was giving hourly updates­ eventually claiming a staggering $10 million haul in a 24-hour period.

Clinton's image took another hit Wednesday when one of Clinton's most prominent backers, former Sen. George McGovern, switched his support to Obama.

The 1972 Democratic presidential nominee said he urged Clinton to drop out of the race, saying it was virtually impossible for her to win the nomination.

"It certainly was not out of any less respect for Sen. Clinton," McGovern said. "I think she has waged a really courageous and valiant campaign. She will have my affection and admiration for all of my days."

"But I think, mathematically, the race is all but won by Barack Obama, and the time has come for all of us to unite and get ready for the general election in the fall," he said.

CNN's Ted Barrett contributed to this report.

All About U.S. Presidential Election • Hillary Clinton • Barack Obama