SEN. JOHN KERRY: The party's 2004 nominee for president, Kerry lost several Western states by razor-thin margins. Obama's campaign has said that three of those states - Nevada, Colorado and New Mexico - are states seen as strong possibilities to turn around Democratic fortunes this year.
SEN. HARRY REID: The Senate majority leader from Nevada is a gold miner's son who has resisted Republican calls for more domestic oil drilling, arguing that the nation should look to solar and renewable energy instead. Reid favors more limits on abortion but voted against the Supreme Court nomination of Chief Justice John Roberts, who is seen as a conservative force on the court and opponent of abortion rights.
GOV. BILL RICHARDSON: New Mexico's governor was among the first Democrats to bow out of this year's presidential race, ending his campaign in January after poor finishes in Iowa and New Hampshire. A former congressman, energy secretary in the Clinton administration and state lawmaker, Richardson brought one of the lengthiest resumes to the presidential race. As a Hispanic, he brought additional diversity to a Democratic field that also included a woman and an African-American.
SEN. EVAN BAYH: The popular Indiana senator and former governor supported Clinton in the primaries, and his speech likely will call on Democrats to unite now behind Obama. A member of the Senate Armed Services and Intelligence committees, Bayh was an early supporter of the war in Iraq.
SEN. JOE BIDEN: Delaware's senior senator ran for president 20 years ago and again this year, dropping out after a disappointing showing in Iowa. He's chairman of the Senate Foreign Relations Committee and is considered experienced in dealing with international affairs. Biden recently traveled to the Republic of Georgia to meet with officials and residents displaced by the Russian invasion.
REP. JAMES CLYBURN: A South Carolinian, Clyburn is the Democratic whip in the House, making him the third-ranking Democrat in the chamber behind Speaker Nancy Pelosi and Majority Leader Steny Hoyer. That job means Clyburn has the assignment of lining up Democratic votes and keeping the party lawmakers in line.
SEN. JACK REED: A military veteran and a defense expert from Rhode Island, Reed traveled with Obama to Iraq and Afghanistan recently. Reed told reporters later that the trip showed Obama could navigate international affairs with competence: "It wasn't just a photo op and social chitchat."
SEN. KEN SALAZAR: Colorado's freshman senator defeated better-funded Republican Pete Coors, chairman of the Coors brewing company, in 2004. Salazar has said Colorado and the West are crucial for a Democratic victory in November, and he blasted Obama's opponent, John McCain, earlier this month for saying a water-sharing agreement among some Western states should be revisited.
RICHARD DALEY: Chicago's five-term mayor and Obama have had a rocky relationship. Obama once passed on a chance to endorse the mayor, and he said last year that corruption at Chicago's city hall gave him "huge pause." Obama later endorsed the mayor. Earlier this year, in the thick of the primary campaigns, Obama stood with Daley in Chicago and heaped praise on him.
FORMER SEN. TOM DASCHLE: The one-time Senate majority leader from South Dakota is a close adviser to Obama. He's submitted information for Obama's vice presidential search. But Daschle has told reporters he is confident he won't be Obama's pick as No. 2.
SEN. JAY ROCKEFELLER: The West Virginian leads the Senate Intelligence Committee and has called the war in Iraq a "catastrophe" that could have been avoided had the Bush administration not concealed information that would have undermined the case for war. First elected to the Senate in 1984, Rockefeller is a great-grandson of oil tycoon John D. Rockefeller and the only Democrat in that family's long political dynasty.
REP. PATRICK MURPHY: The Pennsylvanian is an Iraq War veteran and a Bronze Star recipient. Murphy is among Congress' youngest members at 34 and represents the Philadelphia area. He'll talk about national security along with Tammy Duckworth, a Democratic Iraq War veteran who ran unsuccessfully for Congress from Illinois two years ago and is now Illinois director of Veterans' Affairs.
Democrats say Murphy and Duckworth will put on a tribute to the active-duty military.
REP. ROBERT WEXLER: A chief surrogate for Obama before Jewish audiences, the Floridian backed Obama's compromise plan to seat half the delegates from that state, who were disqualified for breaking party rules and holding a January primary. The compromise angered some Clinton backers, but Wexler called it an "extraordinary concession."
SEN. CHUCK SCHUMER: One of the Senate's top-ranked Democrats, he supported his fellow New York senator, Clinton, during the primaries. Schumer is in charge of the Democratic Senatorial Campaign Committee and published a book last year, "Positively American," in which he argued that Democrats could do a better job winning over middle-class voters.
JEANNE SHAHEEN: New Hampshire's former governor is taking on incumbent Republican Sen. John Sununu in the state. Shaheen narrowly lost her challenge to Sununu in 2002. Democrats believe they could pick off Sununu this year because of a general move away from the GOP by the public and their belief that New Hampshire has become more Democratic in the past six years.
REP. TOM UDALL: The New Mexican is another hope for Democrats to pick up a seat in the Senate. Udall is running to replace retiring GOP Sen. Pete Domenici.
REP. TOM ALLEN: Maine's five-term congressman is challenging Republican Sen. Susan Collins in that state. Though polls show Allen trailing Collins, Allen was handed a victory recently by the Supreme Court, which declined to overturn a Maine court decision keeping an independent candidate off the ballot. The independent, Herbert Hoffman, was thought to be a likely drain on Allen's vote totals.
JEFF MERKLEY: Merkley is speaker of the Oregon House and a Democratic candidate for Senate. Merkley orchestrated a Democratic takeover of the Oregon House two years ago and is taking on incumbent Republican Sen. Gordon Smith.