Keith Ellison, a Democrat, has become the first Muslim to be elected to the US Congress by winning a Minnesota seat in the House of Representatives.
He overcame personal attacks emphasising his past association with Louis Farrakhan, leader of the radical Nation of Islam group.
The 43-year-old lawyer sought to play down the issue of his religion and ran on a populist platform.
He has called for the immediate withdrawal of US troops from Iraq.
On the campaign trail, he also urged a greater reliance on renewable fuels and the establishment of a government-funded universal healthcare system.
"Tonight, we made history," Mr Ellison said in a victory speech to supporters. "We won a key election, but we did much more than that.
"We showed that a candidate can run a 100% positive campaign and prevail, even against tough opposition."
'Not a bigot'
Mr Ellison served two terms as a legislator in the Minnesota House of Representatives and also sat on the Minneapolis City Council.
He converted to Islam while as a student, but talked little about his religious background during the campaign.
Although he follows Islamic law in his personal life, he stresses that he is not the "Muslim candidate" for Congress.
"I'm not running as a Muslim, I'm running as an American, as a person that's trying to help our country be better," he told Voice of America in an interview earlier this year.
"But I do hope that if we win, inshallah [God Willing], in November, that it will signal to Muslims that we should engage in the American political system. It will signal to people who are not Muslims that Muslims have a lot to offer to the United States and the improvement of our country."
He later told the BBC: "I've never been involved in any kind of a bigotry. I've always been a consistent advocate for the human rights of all people. That's my entire adult life. In all the smears that they've thrown at me they've never accused me of saying anything that was bigoted. They've only tried to make guilt by association."
He says his involvement with Louis Farrakhan was limited to a period of a few months, helping to organise the 1995 Million Man March in Washington.
During the campaign, Mr Ellison was supported by the National Jewish Democratic Council as well as a prominent Minneapolis Jewish newspaper, which endorsed him over his Republican rival Alan Fine, who is Jewish.
The Reverend Jesse Jackson, a former candidate for the Democratic presidential nomination, also campaigned for him.
Mr Ellison says his main concern is the middle class.
"The middle class is in a very difficult situation and we need some real change for them," he told Voice of America.
"As we see the middle-class incomes stagnate or go down, we're seeing increasing tuition, and increasing students' debts, and a college education is becoming beyond the reach of the average middle class family.
"We also need for middle-class families to have a real alternative in terms of oil dependency. We need to be able to get around and travel without being dependent upon oil that fluctuates so wildly and unexpectedly."
He has also broken from more conservative Muslims by favouring gay rights and abortion rights, the Associated Press news agency reports.
His election has "huge symbolism", says Larry Jacobs, a professor of political science at the University of Minnesota.
"It's very interesting that Minnesota would be the first state to send a Muslim to Congress," he told Voice of America.
"I think many Americans think of Minnesota as a state that's overwhelmingly dominated by whites, but Minnesota has changed in rapid and dramatic ways. It's seen a large influx of Somalis and immigrants from Asia, particularly Cambodia...
"The other key factor is that Minnesota has a long tradition, stretching back to Hubert Humphrey and Water Mondale, in supporting civil rights and the inclusion of African-Americans and others of colour in the political process."
One of Mr Ellison's Muslim supporters - one of five million Muslims living in the US - also believe his election will make a difference.
"You don't know how much this will be a turnover for the Muslim community that live in the United States in their involvement in the political life," he told the BBC.
"I don't want to be very much optimistic, but at least I can see that my son one day might be the president of the United States."