Live from the floor of the U.S. Senate, it's Sen. Al Franken.
Immediately afterward, the chamber erupted into a applause that lasted for several minutes. Sen. Amy Klobuchar, D-Minn., and former Vice President Walter Mondale -- also a former Minnesota Senator -- escorted Franken onto the Senate floor.
The Associated Press reported that Franken took his oath on a Bible that belonged to the family of Sen. Paul Wellstone, the late Minnesota lawmaker who died in a plane crash in 2002.
Franken's swearing-in gives Minnesota its second senator, now that the eight-month battle over the seat has ended.
Last month, the Minnesota Supreme Court ruled in favor of Franken instead of his challenger, former Sen. Norm Coleman, a Republican.
Franken took to Capitol Hill Monday, where his office already had furniture and there was a staged photo opportunity for reporters of a Senate employee slapping a temporary nameplate on the wall outside.
At a Monday appearance with the Senate Majority Leader Harry Reid, both men tried to draw attention away from the fact that Franken was set to become the 60th Democratic Senator -- so with perfect attendance and unanimity, Democrats could override a Republican filibuster.
But Democrats, two of whom are ill and rarely vote, almost never have perfect attendance and even more rarely have unanimity.
So Reid tried to tamp down expectations for his 60-vote super-majority.
"I'm confident that Senator-elect Franken will make a difference," he said Monday. "But we need more than just his presence to effectively address the nation's many problems. These problems, these challenges we face are not Democratic challenges or Republican challenges or nonpartisan challenges. They're America's challenges, and they're too great to be solved by partisanship," said Reid, arguing that he'll need Republican support for legislation.
"Moving America forward will still require the cooperation of my Senate colleagues, who are Republicans. The last eight years have shown us the American people want us to work together. Democrats aren't looking to Senator Franken's election as an opportunity to ram legislation through this body," he continued.
Reid added that Senate Republicans must understand that Franken's election "does not abdicate from them the responsibilities to govern."
Franken, for his part, said Monday that issues of Republican filibusters are further from his mind than simply representing the people of Minnesota.
"A lot has been made of this number 60," said Franken. "The number I'm focused on is the number two. I -- I see myself as the second senator from the state of Minnesota."
And he'll bring his Midwestern ethos -- "Minnesotans are very practical people," he said -- to the Senate, where his constituents "want to make sure that the work we do here in the Senate makes sense and that the decisions we make for the future have a strong return on investment."