John McCain took a moment to congratulate Barack Obama on his nomination Thursday.

"Too often the achievements of our opponents go unnoticed. So I wanted to stop and say, congratulations," the Republican presidential hopeful says in a new ad released hours before Obama delivers his acceptance speech in Denver.

McCain also noted that Obama's speech coincides with the 45th anniversary of Martin Luther King Jr.'s "I Have a Dream" speech.

"How perfect that your nomination would come on this historic day," McCains says (Watch above). "Tomorrow, we'll be back at it. But tonight Senator, job well done."

A-listers like Ben Affleck, Jennifer Garner, Jennifer Lopez, Jessica Alba and Ashley Judd have been all over Denver showing their support for Obama and Oprah Winfrey is expected to attend his speech at Mile-High Stadium.

See photos of Barack Obama and his family.

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