Lindsey Graham is turning himself into the mad dog of Capitol Hill.

First, the Republican senator from South Carolina opposed Chuck Hagel's nomination to be defense secretary because of Hagel's foreign policy views. Then he argued that Hagel had not produced sufficient background material. Now he's arguing against Hagel because of the administration's handling of the attack on U.S. diplomats in Benghazi, Libya, last September – when Hagel was a professor at Georgetown University.

"I am going to fight the idea of jamming somebody through until we get answers about what the president did personally when it came to the Benghazi debacle," he said in the Senate TV studio Wednesday, a day before his unprecedented filibuster of a nominee to a national security Cabinet post.

"How do you respond to critics who say you're just moving the goal posts?" CNN's Dana Bash asked.

"Oh, I'm going to take every opportunity. I'm not denying it," he answered.

"You are moving the goal posts?" Bash asked. Several of us in the room chuckled.

"No!" Graham said, then explained how he was indeed moving the posts. "I'm going to hit you and keep hitting you, absolutely," he said, raising his voice. Thumping the lectern, he added, "You better believe I'm not going to let this thing go."

Fox News' Chad Pergram pointed out that the treatment he was giving Hagel was in a "rare category."

Graham made a fist. "Am I supposed to sit on the sidelines and be a good compliant Republican and just let this administration not account for what I think is a national security breakdown of monumental proportions?" He added, "I guaran-damn-tee you" that Democrats would treat a Republican president even worse.

And I guaran-damn-tee you this: Graham's antics have as much to do with events in Columbia, S.C., as with events in Washington. His sentiments are no doubt genuine, but the ferocity with which he has been attacking the Obama administration – taking a high-profile role on Benghazi, Susan Rice, Hagel and gun control – are helping him to repel a tea party primary challenge at home.

Graham acknowledged the pressure when I asked him about the influence of home-state politics on his recent actions. "You know, I'm in a red state. I know I'm always exposed in a Republican primary," he said. But he argued, correctly, that he continues to take a leading role on immigration, which infuriates many conservatives.

"I think it's positive for me to one day beat the hell out of them and the next day see if we can do a deal," he said. He described his role in the opposition as a balance between saying "yes for the common good of the country where you can" and saying "no because you need to."

The problem is that Graham, to get through the 2014 primary, needs to say "no" more often now. And Congress can hardly afford for one of its few remaining deal-makers to take an obstreperous turn. But perhaps Graham should be given some slack. The Republican primary system has gone haywire, and this may be the only way a sensible lawmaker can survive it.

Not too long ago, Graham had been in deep trouble with South Carolina conservatives because of his talk about climate-change legislation, his votes for both of Obama's Supreme Court nominees, his criticism of the Bush administration's wiretapping and interrogation programs, and his championing of "Grahamnesty" immigration reforms.

But the gradual repositioning has apparently worked. A survey by Public Policy Polling in December found that the percentage of Republicans saying they would vote for him in a primary has climbed to 51 percent from 37 percent in January 2011.

And Graham isn't letting up. At a hearing on gun control, he unnerved a witness, a U.S. attorney, by beginning his questions with a blunt inquiry: "Do you own a gun?" At a Benghazi hearing, he got the chairman of the Joint Chiefs of Staff to admit he was "surprised" about Hillary Clinton's ignorance of the ambassador to Libya's request for more security shortly before he was killed.

And Graham delivered a memorable hectoring of Hagel for the nominee's prior claim that lawmakers are "intimidated" by the Israel lobby. "Name one," Graham challenged. Hagel couldn't.

Graham, who has voted the conservative line 90 percent of the time over his career, argues that his new positions are consistent with his previous ones – and they are. But the difference is in the emphasis. In order to survive the Republicans' backward primary system, Graham needs to de-emphasize anything that might make him appear to be reasonable.

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