WASHINGTON (CNN) -- Sen. Barack Obama closed in Friday on Sen. Hillary Clinton's lead among superdelegates, the Democratic officials who hold the balance of power in determining the party's presidential nominee.
The Obama campaign announced the support of seven superdelegates, including a previous Clinton backer.
Hawaii Rep. Mazie Hirono, New Mexico Democratic Party member Laurie Weahkee and South Carolina Democratic Party Vice Chair Wilber Lee Jeffcoat, announced they are backing the Illinois senator.
Other superdelegates that pledged their support to Obama on Friday include: California Democratic National Committee member Ed Espinoza; Rep. Peter DeFazio of Oregon told The Oregonian newspaper that he will support Obama's bid.
Oregon voters are in the middle of primary voting, which takes place through the mail.
Rep. Donald Payne, a New Jersey Democrat and an early Clinton supporter, told The [Newark] Star-Ledger that he was switching to Obama.
Another superdelegate, John Gage, president of the American Federation of Government Employees, also said he is backing Obama. He had been uncommitted. His union, which is affiliated with the AFL-CIO, said it represents more than 600,000 workers.
CNN has also confirmed five new superdelegates for Clinton, though they all endorsed the New York senator before the primaries in Indiana and North Carolina.
Neither candidate has the 2,025 delegates needed for the nomination. Obama has 1,860 total delegates, 165 delegates short of clinching the Democratic nod, and Clinton has 1,696, according to a CNN survey.
Obama holds a commanding lead in the number of pledged delegates awarded from primaries and caucuses: 1,592 to Clinton's 1,424.
The latest announcements narrow Clinton's lead in superdelegates to single digits. At the year's start, she led by more than 100 superdelegates. Watch as the momentum appears to be in Obama's favor »
There are 217 pledged delegates up for grabs in the remaining contests.
After Clinton's narrow win Tuesday in Indiana and and her double-digit loss in North Carolina, former Sen. George McGovern, the 1972 Democratic presidential nominee, said he had decided to back Obama over the former first lady. McGovern is not a superdelegate.
A Virginia superdelegate -- Jennifer McClellan, a member of the state House of Delegates from Richmond -- moved over to Obama, too.
Nevertheless, the Clinton campaign said it had picked up the support of Rep. Christopher Carney of Pennsylvania.
Clinton is not going down without a fight, making pitches Friday to superdelegates that she is the best candidate to lead a Democratic ticket in November.
Her campaign tried to appeal to elected Democrats in Republican-leaning districts, arguing that Clinton can win more votes there than Obama and thus help their re-election prospects.
In a PowerPoint presentation e-mailed to the nearly 800 superdelegates, the campaign detailed how she had defeated Obama in GOP-leaning congressional districts and had consistently topped him among key voting blocs such as senior citizens and Hispanics. View the PowerPoint presentation
Despite those efforts, the Clinton camp already appears to be planning an exit strategy, according to Lawrence O'Donnell, a Huffington Post contributor who cited Clinton insiders.
"They are saying that Hillary will be out of the race by June 15," O'Donnell said Friday on CNN's "American Morning."
"What the senior campaign official has told me is that they will go through the final votes on June 3.
"Remember, Hillary is going to win maybe three of the elections, and Obama is going to win maybe three elections coming out of it," he said, referring to the remaining six contests. Watch what O'Donnell says Clinton insiders are saying behind doors »
O'Donnell said the Clinton campaign then would make its case to the superdelegates for about a week after the primaries ended.
"The superdelegates have no chance of moving over to Hillary Clinton in a week," he said. "So for the Clinton campaign to say we will only make the case for a week, and then by June 15, we will have a nominee, that is to say she will drop out."
Meanwhile, former Democratic contender John Edwards said Friday on NBC and MSNBC that Obama is the likely nominee. Edwards is not a superdelegate.
Both the Clinton and Obama campaigns have heavily wooed the former senator from North Carolina since he ended his presidential run in January, but he has not publicly endorsed either candidate.
Edwards said Friday that he worried the continuing campaign could take a toll on the Democratic Party's chances in November.
"I think it's fine for Hillary to keep making the case for her," he said on MSNBC's "Morning Joe." "But when that shifts to everything that is wrong with [Obama], then we're doing damage instead of being helpful."
On Thursday, Obama paid an unusual half-hour visit to the floor of the House of Representatives, where lawmakers greeted him enthusiastically. He denied that he was campaigning, saying he was "just saying hello."
"There are some undecideds" in the House, Obama said as he was leaving. "If they have questions for me, then I'm certainly happy to respond to them."
There are more than 70 undeclared Democrats in the House.
Obama made clear he is willing to campaign through the remaining contests if Clinton does not drop out before the last one June 3.
"Sen. Clinton is a formidable candidate. She is very likely to win West Virginia and Kentucky. Those are two states where she has insurmountable leads," he said. "We're going to have spend some time there. But we're also going to Oregon, Montana, South Dakota and Puerto Rico."
In an interview Thursday with Wolf Blitzer on CNN's "The Situation Room," Obama deflected a question about a potential joint ticket with Clinton, saying it's too early to start thinking about running mates. Watch the interview with Obama »
"Sen. Clinton's ... tireless, she's smart, she's capable, and so obviously she'd be on anybody's short list to be a potential vice presidential candidate," he said. "But it would be presumptuous of me at this point ... to somehow suggest that she should be my running mate."
CNN's Mark Preston, Rob Yoon, Rebecca Sinderbrand, Richard Allen Greene, Ed Hornick and Alexander Mooney contributed to this report.