DENVER, Aug. 28 (UPI) -- Sen. Barack Obama's historic campaign for the U.S. presidency begins anew Thursday, when he accepts the Democratic party nomination in Denver.

Up to 75,000 people were expected at Invesco Field to listen to the senator from Illinois, which party leaders said in a statement they anticipated would concern the urgency of change.

Obama was declared the party's presidential nominee Wednesday by acclamation, becoming the first African-American to lead a major party's presidential bid.

The final session of the Democratic National Convention, with the theme "Change You Can Believe In," includes a tribute to Martin Luther King Jr., who delivered his seminal "I Have a Dream" speech" exactly 45 years ago from the steps of the Lincoln Memorial in Washington.

Among the scheduled speakers are New Mexico Gov. Bill Richardson, who also sought the 2008 Democratic presidential nomination; Virginia Gov. Tim Kaine, who was under consideration as Obama's running mate until Sen. Joe Biden of Delaware was tapped. Sen. Dick Durbin of Illinois is the scheduled final speaker before Obama delivers his acceptance address.

Michelle Obama doesn't want to jinx run

DENVER, Aug. 28 (UPI) -- Michelle Obama says she doesn't want to jinx her husband's historic run at the U.S. presidency by commenting on his chances of winning the White House.

Saying she's "a bit superstitious" about discussing Barack Obama's being the Democratic presidential nominee, Michelle Obama said Thursday on NBC's "Today Show," "We just do the work. You know, I don't want to jinx it. I don't want to get too far ahead of myself."

Obama was declared the party's nominee Wednesday by acclamation at the Democratic National Convention in Denver. The first major-party black presidential candidate delivers his acceptance speech Thursday, 45 years to the day after civil rights leader Martin Luther King Jr. delivered his "I Had a Dream" speech on the steps of the Lincoln Memorial in Washington.

Obama said she tries to remain focused and not allow comments by Republicans and their presumptive presidential nominee John McCain bother her.

"We know that part of politics is shaping, recasting, all that stuff," Obama said. "And I know that this election isn't about me."

Bush's speech to make case for McCain

WASHINGTON, Aug. 28 (UPI) -- U.S. President George Bush will speak at the Republican National Convention in Minnesota to boost John McCain, not rehash his tenure, the White House said.

Bush is scheduled to speak Monday. the opening day of the convention in St. Paul. during which McCain, a U.S. senator from Arizona, is to be named the party's presidential nominee.

Bush's speech "will focus on John McCain and why he's the right person to be president of the United States and looking forward rather than looking back," White House press secretary Dana Perino said Thursday during a news briefing. "It will not be a reprise of the past 7 1/2 years."

After his speech, Bush has "decided that he would follow precedent from other presidents who got out of town because ... he is not on the ballot," Perino said. "This is about John McCain and we intend to allow the spotlight to shine fully on him during this convention next week."

Rezko may be cooperating with feds

CHICAGO, Aug. 28 (UPI) -- Tony Rezko, a Chicago developer and one time fundraiser for Barack Obama, may be being pressured by federal investigators to tell on Illinois politicians.

Rezko has been jailed since June while awaiting sentencing in October on mail and wire fraud, aiding and abetting bribery and money laundering convictions. He faces two more trials.

The Chicago Sun-Times said Thursday that sources said Rezko has been seen a dozen times at the Chicago federal courthouse and, one source said, has been twice in the office of the U.S. attorney. This has raised speculation he is cooperating in "Operation Board Games," an ongoing probe into state corruption that allegedly may reach all the way to Democratic Gov. Rod Blagojevich.

Rezko's work as an adviser and fundraiser for Blagojevich may be of special interest to federal authorities, sources told the Sun-Times.

Rezko lawyer Joseph Duffy called the idea of his client's involvement in other prosecutions "bogus." He noted that his lawyers have permission to meet with him at the courthouse, the Sun-Times said.