Seven senators who have embraced same-sex marriage in 2013

Sen. Kay Hagan (D-N.C.) on Wednesday became the seventh senator and sixth Senate Democrat to announce her support for same-sex marriage this year.

The other senators who have shifted their positions in the last month are Rob Portman (R-Ohio), Mark Begich (D-Alaska), Claire McCaskill (D-Mo.), Mark Warner (D-Va.), Jay Rockefeller (D-W.Va.) and Jon Tester (D-Mont.). Portman is the only Republican senator to back gay marriage.

Only nine Senate Democrats have not publicly embraced same-sex marriage, according to a report by Time magazine. 

Sens. Mark Pryor (Ark.), Tom Carper (Del.), Bob Casey Jr. (Pa.), Joe Donnelly (Ind.), Tim Johnson (S.D.), Heidi Heitkamp (N.D.), Mary Landrieu (La.), Joe Manchin (W.Va.) and Bill Nelson (Fla.) are the Democratic senators who have not backed gay marriage.

Polls show a majority of voters now support gay marriage, and Democratic politicians in particular have raced to side themselves with public opinion. 

President Obama announced his support for gay marriage last year, and earlier this month former Secretary of State Hillary Clinton said she supported gay marriage. 

The Supreme Court has heard two cases on the issue this year. Many expect the court will strike down the federal Defense of Marriage Act, which prohibits same-sex couples from getting certain benefits offered to married couples.

It's unclear whether more Senate Democrats or Republicans will shift their positions in the coming days. 

Manchin, Johnson and Pryor have expressed opposition to gay marriage, while Landrieu and Donnelly did not respond to requests for comment from Time, according to the publication's report. All five hail from states that Obama lost in the 2012 presidential election, though Obama did win Indiana in 2008.

Casey, Carper, Heitkamp and Nelson do not back same-sex marriage. All four have either opposed new legislation banning same-sex marriage or been clear proponents of civil unions and rights for same-sex couples.

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