(CNN) -- Declaring that Sen. Barack Obama is an "extraordinary American," Gov. Bill Richardson of New Mexico endorsed Obama for the Democratic nominee for president on Friday.

Richardson -- who sought this year's Democratic nomination for president himself -- joined Obama at a rally in Portland, Oregon, where the senator from Illinois is campaigning.

"Barack Obama will make a great and historic president," Richardson said, Obama standing at his side. "[It] is a once-in-a-lifetime opportunity for our nation and you are a once-in-a-lifetime leader."

Obama said, "I am extraordinarily grateful to have the support of one of the great public servants of these United States." Watch more of the endorsement »