(CNN) - The chief investigative correspondent at ABC News on Sunday defended the timing of an interview with Newt Gingrich's ex-wife and denied the presidential candidate's allegation that the network was biased against conservatives.
Brian Ross told CNN's "Reliable Sources" host, Howard Kurtz, that he had been trying to secure the interview with Marianne Gingrich since last November.
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The interview was broadcast on Thursday night, meaning there was "one news cycle to allow Mr. Gingrich to respond, and respond he did," Ross said.
Gingrich's angry response to a question about the interview from CNN moderator John King to start Thursday night's debate has been widely credited with helping turn Saturday's South Carolina primary vote in his favor.
Appearing on the CBS program "Face the Nation" later Sunday, Gingrich said the ABC report, and questions about his ex-wife, didn't play well with South Carolina voters.
"I think you saw the people of South Carolina agreed it was totally inappropriate," Gingrich said, later adding: "I was amazed at how intense the feeling was that night, that people just repudiated that kind of trash in the campaign."
Gingrich also said the timing of the ABC report revealed a possible bias in favor of rival candidate Mitt Romney.
"The way they did it, it was almost as if ABC was an arm of the Romney campaign," Gingrich said.
Ross pointed out in his interview, which was conducted before Gingrich's comments to CBS, that the story on Gingrich's ex-wife ran the day after another report by Ross about how Romney had millions of dollars in funds held offshore in the Cayman Islands.
Later in the interview, Ross denied an allegation made by Gingrich in Thursday night's debate that his campaign had offered several friends to ABC to prove that Marianne Gingrich's story was false.
"That simply is not true," Ross said, adding the Gingrich camp only offered his two daughters, who were featured in the "Nightline" report. "Nobody else was offered to us at all and our request to talk with the speaker himself was also denied by the campaign."
On the claim that ABC has an anti-conservative agenda, Ross noted that he faced similar charges from Barack Obama's supporters in 2008 when he reported on Rev. Jeremiah Wright, the then-candidate's former pastor.
"We're not out to get anybody. We're out to cover the news and to frame what's going on in this campaign," Ross said.
Ross said Gingrich's past marital infidelities were a viable topic for discussion.
"I think moral character is a relevant factor for every candidate running for president, and he [Gingrich] has campaigned on a platform involving policies that are family values and the sanctity of marriage. So I think, yes, it is an issue," he said.
Ross also stood by his report on Romney's offshore holdings. He pointed to a Wall Street Journal report that contradicted the Romney campaign's assertion that no tax advantages came from holding money offshore.
"We can't really know without seeing Romney's tax returns, which to this point he has not released or made public," Ross said.
Romney committed Sunday to releasing his tax records on Tuesday.