As speculation mounted about a possible joint ticket after the Democratic primaries, Clinton's campaign released a statement: "While Sen. Clinton has made clear throughout this process that she will do whatever she can to elect a Democrat to the White House, she is not seeking the vice presidency, and no one speaks for her but her. ... The choice here is Sen. Obama's and his alone."
But after a bitterly-fought Democratic primary battle, supporters close to Clinton believed she wasn't eager to be Obama's vice presidential candidate.
Publicly, Clinton has enthusiastically endorsed the presumptive Democratic nominee and embraced his vision for the country.
"This isn't exactly the party I'd planned, but I sure like the company," she told a crowd of thousands of supporters, mostly women, who came to hear her June concession speech at the National Building Museum in Washington.
"I am standing with Sen. Obama to say, 'Yes we can,'" she said.
But as the general election heated up, Clinton appeared to be laying low, publicly rededicating herself as the senator from New York rather than a high-profile Obama surrogate.
And there are signs the New York senator may be quietly laying the groundwork for a presidential run in 2012.
After her defeat, Clinton sent donors an e-mail noting that she would welcome contributions of general election funds they donated to her presidential campaign to her anticipated 2012 Senate bid.
But those funds from her Senate account could be transferred into a possible 2012 bid for presidency, if Clinton decides to run.
The Markham Group -- a firm that directed all of Clinton's advance work -- also purchased the Web site HRC2012.com, though a Clinton spokesperson denied the site may be early groundwork for another presidential bid.
"The only 2012 race she is interested in is her Senate re-election bid," Mo Elleithee told ABC News.
Many Democrats close to both senators say tensions remain between the ex-rivals.
Clinton has publicly campaigned with Obama only once since losing the Democratic primary -- a day of choreographed unity at a Democratic rally in Unity, N.H., where the once-bitter rivals held hands and praised each other before a throng of news cameras.
"I've admired her as a leader; I've learned from her as a candidate," Obama told a cheering crowd of 4,000. "She rocks. She rocks. That's the point I'm trying to make."
Clinton headlined a few solo campaign rallies for Obama in Florida and Nevada in August, urging her supporters to vote against Republican candidate Sen. John McCain, R-Ariz.
"Anyone who voted for me or caucused for me has so much more in common with Sen. Obama than Sen. McCain," she said in Henderson, Nev., on Aug. 8.
Despite the public displays of unity, Democrats who witnessed an Obama fundraiser with Clinton's top donors in June reported it as more awkward than unifying.
"This felt like when your mom forces you to go visit your Aunt Ida and she has to pinch your cheeks and you're sitting there in an uncomfortable suit and you can't wait to leave," a top Clinton donor told ABC News' Kate Snow.
Clinton supporters also are angry Obama hasn't done more to help his ex-rival pay off her $25.2 million campaign debt, including her own $13.2-million personal loan to the campaign.
They were infuriated when Obama had to be reminded to ask donors at a fundraising event this summer to help Clinton.