Online petition drives are urging Sen. Joe Donnelly, D-Ind., to support same-sex marriage.
The liberal advocacy organization MoveOn.org identified Donnelly as among eight Democratic senators who are "holdouts on marriage equality." On its website, MoveOn has linked the names and photos of the lawmakers to petitions asking them to oppose the Defense of Marriage Act.
The petition for Donnelly had been signed by 2,522 people by Tuesday evening, according to the website. Only the petition for Sen. Bill Nelson, D-Fla., had more signatures – 3,632.
MoveOn on Tuesday issued a "victory update" after one of the eight senators, Delaware's Tom Carper, announced he now supports gay marriage. Also Tuesday, Illinois Sen. Mark Kirk became the second Republican in the chamber to give his support, joining Ohio's Rob Portman.
Meantime, a Columbus, Ind., blogger for the liberal website Daily Kos is asking readers to sign an online petition encouraging Donnelly to back same-sex marriage.
"Senator Donnelly's office is aware of the petitions and welcomes Hoosiers on both sides of the issue to contact his office," Elizabeth Shappell, communications director for Donnelly, said Tuesday in an email.
Donnelly was asked about his views on same-sex marriage during a news conference in Fort Wayne on March 26. The same day, the U.S. Supreme Court was hearing arguments in a challenge to California's law that restricts marriage to heterosexual couples.
"I have said that I believe that marriage is between a man and a woman," Donnelly at the time. "But I'm keeping an eye on this. This area continues to move very quickly. And so I'm watching to see what happens, not only in the court but also in our communities as well."
Asked Tuesday whether Donnelly has altered his stance since then, Shappell said he "continues to review the issue."