By midday Tuesday, Sen. Barack Obama (D-Ill.) had picked up three House superdelegates, as well as the backing of other party officials with a vote at the Democratic convention.

Obama was endorsed Tuesday by Reps. John Olver (D-Mass.), Congressional Black Caucus Chairwoman Carolyn Cheeks Kilpatrick (D-Mich.) and James Clyburn (D-S.C.), the highest-ranking African-American in the House.

Clyburn said that Rep. John Spratt (D-N.C.) is likely to endorse Obama later Tuesday afternoon and that House Speaker Nancy Pelosi (D-Calif.) planned to make a statement on the race either Wednesday or Thursday.

Furthermore, Obama picked up the support of Debbie Dingell, wife of Rep. John Dingell (D-Mich.) and a key party operative in Michigan.

That leaves the Illinois Senator, according to his campaign Web site, with 35.5 delegates to go to clinch the Democratic presidential nod. Obama must have a total of 2,118 delegates to secure the nod.

Obama hopes to be able to claim victory Tuesday night over his rival for the nod, Sen. Hillary Rodham Clinton (D-N.Y.), having won a clear lead among pledged delegates. He has reserved the Xcel Energy Center in St. Paul, Minn., site of the Republican National Convention, for his speech Tuesday evening.

Although the Associated Press reported Tuesday morning that Clinton was preparing to concede in her speech Tuesday night after the end of the Democratic primary season, Clinton spokesmen have vociferously denied that report.

— Steven T. Dennis and Lauren W. Whittington