Sen. Rob Portman, right, and his son, Will are seen in this undated family photo. (Image Credit: Office of U.S. Sen. Rob Portman/AP Photo)

The Republican Party won't suffer from its opposition to same-sex marriage, according to one of the only two GOP senators who support it publicly.

"I'm not particularly worried about it," Sen. Rob Portman of Ohio told Politico's Mike Allen at an economy-focused breakfast event in Washington, D.C., this morning. "I think for most Americans, the top issue is what we're talking about here today, which is jobs and the economy; how to get this economy moving in a way that provides opportunity."

Asked about GOP reaction to same-sex marriage as a topic of political discussion, the Ohio Republican senator and former Romney VP short-lister described the party's reaction as "mixed."

"Mixed, and that's understandable," Portman said, when Allen asked him, of the GOP, "Do you think they sort of get it, or do you think there's a ways to go?"

Portman added: "After all, I had a different point of view until very recently. No, it's a mixed reaction. … I'm sure there are other political impacts, but for me this was not a political decision."

Some in the party, and outside it, have worried that Republicans have taken a losing stand, politically, against same-sex marriage. At a panel hosted by the GOP gay-rights group GOProud at the Conservative Political Action Conference (CPAC) in Maryland last month, strategists and conservative columnists openly fretted that the Republican Party deploys intolerant rhetoric and policies that will alienate a generation of new voters.

Portman became the only GOP senator to support gay marriage when he announced his backing March 15, revealing that his son is gay. That made Portman one of just three sitting Republican lawmakers to support gay marriage, along with Reps. Richard Hanna of New York and Ileana Ros-Lehtinen of Florida.

Sen. Mark Kirk of Illinois the only other GOP senator who supports it.

Perhaps spurred by Portman, and by Supreme Court arguments on Prop. 8 and DOMA last month, a cascade of Senate Democrats have followed Portman's lead, as ABC News' Sunlen Miller has reported.

Polls reflect Portman's impression that the economy, deficits and health care rate as the top three issues of priority for Americans. On same-sex marriage, most side with Portman and against the rest of his party.

In the last ABC News-Washington Post poll, released March 18, 58 percent of respondents said they think gay marriage should be legal.