"To the people of Minnesota, let me say this: I'm not a perfect person," said Franken, a former writer and performer for the "Saturday Night Live" TV comedy show. "I'm not going to pretend to have all the answers. But I'll tell the truth, I will keep my spine, and I will work for you."
Franken's only competitor, college professor and peace activist Jack Nelson-Pallmeyer, withdrew after Franken passed the necessary 60 percent threshold on the first ballot. Nelson-Pallmeyer proposed that delegates unanimously back Franken, putting him over the top.
Franken's show of strength came as something of a surprise after a rocky few weeks in which some Democrats, led by U.S. Rep. Betty McCollum, criticized a racy column he wrote for Playboy magazine in 2000 and, earlier this week, joking comments he was reported to have made about rape that were included in a 1995 New York magazine article about "Saturday Night Live."
Rumors flew that Franken's support was collapsing, and that other candidates were considering a late entry into the endorsement stakes. Franken finally tackled the controversy head-on in his nomination speech to delegates, where he said some of the things he said and wrote over 35 years as a writer were "downright offensive."
"I understand that," said Franken. "And I understand that the people of Minnesota deserve a senator who won't say things that make them feel uncomfortable."
As a best-selling satirist and commentator for a liberal talk radio network, Franken was known for lampooning conservative commentators like Rush Limbaugh and President George W. Bush.
Nelson-Pallmeyer said he would work for Franken's election and won't run in the Democratic primary in September, and for now Franken is facing no opposition. But trial attorney Mike Ciresi, who dropped out of the endorsement race several months ago, has said in recent days that he is considering running in the primary.
Republicans have also hammered Franken for months on some of the more outrageous comments and writing from his years as a comedian, as well as problems with his personal finances. They promised to keep up the heat now that he is the chosen Democratic candidate.
Coleman campaign manager Cullen Sheehan attacked Franken as "unqualified, unfit and unprepared to be a United States senator." He said the campaign will employ old Franken material.
"Al Franken wants to wants to talk about Norm Coleman's record. We're not going to be shy about talking about Al Franken's record," Sheehan said.
As he wooed delegates throughout the day, Franken used the Republican assault as a badge of honor and touted himself as someone who can take the fight right back to the Republicans.
"The Republicans don't want me to be the nominee," Franken said. "But guess what? Thanks to you, I'm going to be, and guess what? I'm going to beat Norm Coleman by holding him accountable."
On Saturday morning, Franken took a key step in quelling controversy over his past jokes when he earned the endorsement of the feminist caucus of the Democratic-Farmer-Labor Party, as the Democratic Party is known in Minnesota.
Jackie Stevenson, the group's leader, said the caucus was impressed with his direct answers on issues critical to members, including domestic violence. She said the group was willing to look past salacious material from Franken's past that some have considered degrading to women.
"At the time he didn't realize how it would affect him later in life," Stevenson said. "He wouldn't do it again today."