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."