Obama nomination due today

After a full-throated call for unity by Sen. Hillary Rodham Clinton, delegates at the Democratic National Convention prepared to formally nominate Barack Obama for president Wednesday and make the Illinois senator the first black nominee of a major political party.

Obama was scheduled to arrive in Denver Wednesday night as the convention heads into its third day, featuring speeches by vice presidential nominee Joe Biden and former president Bill Clinton.

Obama also arrives amid some confusion over how today's historic nomination process would roll out.

Representatives of Clinton and Obama may have struck a deal setting ground rules for Wednesday's roll call vote that will hand the nomination to Obama. But the vote may also allow disaffected Clinton backers to express their support for her.

Advisers to Clinton and Obama sent a joint letter to state delegation chairs instructing them to distribute vote tally sheets to delegates Wednesday and return them before the vote is scheduled to get underway at 6 p.m. ET.

The letter, first obtained Tuesday night by the Associated Press, said Clinton would have one nominating speech and two seconding speeches, followed by Obama's nominating speech and three seconding speeches — totaling no more than 15 minutes for each candidate. Then the roll call will begin, said the letter signed by Obama senior adviser Jeff Berman, Clinton senior adviser Craig Smith and convention secretary Alice Germond.

The call of states will continue until all votes are counted or someone asks the delegates to give the nomination to Obama by acclamation.

Whether each delegation accepts the process remained unclear Wednesday morning.

"It's not Hillary's job to bring this party together," said Jennie Lou Leeder, a Clinton delegate from Llado, Texas. "It's Barack Obama's job to bring this party together."

Yet that's exactly what Clinton called for Tuesday night, calling Obama "my candidate."

"I want you to ask yourselves: Were you in this campaign just for me?" she said.

Party officials have fretted over the in-fighting since the convention began Monday, worried that it would take away from Obama's historic moment.

"All you need is 200 people in the crowd to boo and stuff like that and it will be replayed 900 times," said former Democratic National Chairman Don Fowler. "And that's not what you want out of this."

After Wednesday's nomination and Thursday night's acceptance speech by Obama at Invesco Field at Mile High, his campaign will begin a cross-country bus tour to speak with voters about their "economic challenges" and lay out their blueprint for a solution.

With Obama, Biden and both their wives on board, the "On the Road to Change" bus tour will begin Friday in Beaver, Penn., and then roll through Michigan and Ohio — all key swing states in the November election.

Contributing: Associated Press