"Sen. Obama brings a new vision for our future and new voters to our cause. He has created levels of energy and excitement that I have not witnessed since the 1960s," read Clyburn's Tuesday statement.
Many prominent Democrats, including House Speaker Nancy Pelosi, have urged fellow Democrats to vote the way their state does.
The role of superdelegates may be given more scrutiny after the grueling, neck-and-neck primary battle between Obama and Clinton.
The Democratic Party decided more than three decades ago that party leaders and former Democratic politicians should become the ultimate deciders in a tight race.
After the insurgent outsider campaigns of George McGovern and Jimmy Carter won the Democratic Party nominations in 1972 and 1976, many party officials felt the need to have a greater role in the nominating process.
Apart from convincing big numbers of undecided superdelegates to back her presidential bid, the only option left to Clinton is to push her fight to the Democratic convention in late August, a move opposed by party leaders eager to stop the infighting and start fighting against McCain.
With her considerable support from voters, Clinton may also be trying to leverage herself to negotiate with Obama on various matters, including a potential spot on the ticket as the vice presidential candidate or influence Obama on policy issues, like health care.
Asked Tuesday by a South Dakota radio station about a potential vice presidential choice, Obama said, of Clinton, "She's run a magnificent race ... I'm sure that we will have ample time to sit down and talk about bringing the party together and make sure that we are focused on November."
Entering the general election with a Republican president with record-low approval ratings and polls suggesting over 80 percent of Americans believe the country is on the wrong track, Obama has a good shot at the White House.
However, Obama emerges bruised from a bitter Democratic primary battle, and faces the daunting challenge uniting the party.
The Democratic nomination fight exposed Obama's challenges in gaining support from white, blue-collar voters, Hispanics, women, and older voters who supported Clinton's candidacy in huge numbers.
With reporting by ABC News' David Wright, Jake Tapper, Karen Travers, Rick Klein, Kate Snow, Sunlen Miller, Karin Weinberg, Eloise Harper and James Gerber.