8 weeks until votes are counted, Barack Obama leads Mitt Romney 50% to 40% in the battle for Minnesota's 10 electoral votes, incumbent DFL candidate Amy Klobuchar is materially ahead in her campaign for re-election to the U.S. Senate, and an amendment to define marriage is narrowly favored to pass, according to a SurveyUSA poll conducted for KSTP-TV in the Twin Cities.

In this, SurveyUSA's first poll of Minnesota since the Republican and Democratic conventions, Obama's lead over Romney has grown from 6 points 6 weeks ago to 10 points today. The 10-point advantage comes largely from women, among whom Obama today leads by 17 points. Romney leads in Southern MN, but Obama leads elsewhere in the state. Obama holds slightly more of the Democratic base than Romney holds of the Republican base, and Independents break ever-so-slightly for Obama. (Among Independents, there has been a 7-point swing to Obama compared to SurveyUSA's poll 6 weeks ago.) The real tailwind comes from moderates, who break 2:1 for Obama. Romney trails among the rich and the poor, among the educated and the less educated. There is erosion in Romney's support among middle-income and upper-income voters, compared to 6 weeks ago.

Today's release is also SurveyUSA's first poll in Minnesota since Paul Ryan was named Romney's running mate. 30% of likely voters say Ryan makes them more likely to vote for Romney, but 34% say Ryan makes them more likely to vote for Obama. 35% shrug when asked about Ryan.

An amendment to define marriage in Minnesota as between one man and one woman is today favored to pass 50% to 43%, though all ballot measures are difficult to predict. Today, SurveyUSA finds: Republicans favor the amendment 4:1. Democrats oppose the measure 2:1. Independents split. The less educated you are, the more likely you are to support the amendment. The lower your income, the more likely you are to support the amendment. An odd coalition takes shape, age-wise: voters younger than 35 and older than 64 support the measure. Voters age 35 to 64 split. SurveyUSA has polled on the marriage amendment before, going back to 2011. This is the first poll that used the actual language that will appear on the ballot, instead of a summary of the ballot language; previous SurveyUSA polls are not apples-to-apples comparable with this one.

In the election for U.S. Senator from Minnesota, incumbent DFL candidate Amy Klobuchar remains the overwhelming favorite, leading Republican Kurt Bills 55% to 34%. 6 weeks ago, Klobuchar led by 24 points, today by 21.

Cell-phone and home-phone respondents included in this research: SurveyUSA interviewed 700 adults 09/06/12 through 09/09/12. Of them, 627 were registered to vote. Of the registered, 551 were determined by SurveyUSA to be likely to vote in the 11/06/12 election. This research was conducted using blended sample, mixed mode. Respondents reachable on a home telephone (77% of likely voters) were interviewed on their home telephone in the recorded voice of a professional announcer. Respondents not reachable on a home telephone (23% of likely voters) were shown a questionnaire on their smartphone, tablet or other electronic device. Obama leads by 4 points among voters interviewed on their home phone. Obama leads by 25 points among voters not reachable on a home telephone. When the two groups are proportionally combined, Obama leads by the 10 points reported here. In 2008, Obama carried Minnesota by 10 points over John McCain.