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Hillary Clinton denied Thursday that she began publicly supporting same-sex marriage last year for political reasons, after initially opposing it.

In a tense interview with NPR’s Terry Gross Thursday, Clinton accused the radio host of “playing with her words” after Gross repeatedly pressed Clinton about her change in stance on gay marriage.

At one point, Clinton told Gross: "I think you're being very persistent, but you are playing with my words and playing with what is such an important issue."

Gross said she was trying to clarify Clinton's views on the issue.

"No, I don't think you are trying to clarify," Clinton responded. "I think you are trying to say that I used to be opposed and now I am in favor and I did it for political reasons. And that's just flat wrong. So let me just state what I feel like you are implying and repudiate it."

Clinton added: "I have a strong record. I have a great commitment to this issue and I am proud of what I've done and the progress we're making."

The exchange came during Clinton's media tour supporting her new book, "Hard Choices," about the former first lady and senator's time as President Obama's secretary of state. Clinton has said she'll decide later this year whether to make a second run for president.

In 2008, Clinton, Barack Obama and other Democratic presidential candidates opposed legalizing same-sex marriage, although they endorsed versions of civil unions.

In March 2013, Clinton released a video expressing her support for gay marriage, shortly after she left the State Department. As the nation's top diplomat, Clinton refrained from weighing in on domestic politics but she won praise from gay rights organizations for bringing attention to LGBT issues around the globe and within the State Department.

Clinton told Gross during the interview broadcast on "Fresh Air” that she “did not grow up even imagining gay marriage and I don't think you did either.”

"This was an incredibly new and important idea that people on the front lines of the gay rights movement began to talk about and slowly, but surely, convinced others about the rightness of that position," she added. "When I was ready to say what I said, I said it."

The former first lady's announcement came after Obama, Vice President Joe Biden and several prominent Democrats — along with Republicans like Ohio Sen. Rob Portman — had stated their support for same-sex marriage.

Gross noted that Clinton's husband, former President Bill Clinton, signed the Defense of Marriage Act, which defined marriage as a union between one man and one woman and denied gay couples a range of federal marriage benefits.

The former New York senator said the nation is "living at a time when this extraordinary change is occurring and I'm proud of our country." She said that in 1993, at the start of her husband's presidency, "that was not the case."

Gross asked Clinton if her views had evolved since the 1990s.

Clinton said, "I'm an American ... I think that we have all evolved and it's been one of the fastest, most sweeping transformations that I'm aware of."

Clinton also criticized those opposed to legalizing same-sex marriage, saying they are never open to change and live in an “evidence-free zone.” She said she believes it is good for people to continuously change.

“One of my big problems right now is that too many people believe they have a direct line to the divine and they never want to change their mind about anything,” she said.

Clinton was appearing at several events in New York to promote her book.

The Associated Press contributed to this report