Sen. John Cornyn has always relished and excelled in the role of attack dog, and now that the Texas Republican has been installed as his party’s chief antagonist in the Senate, he’s come out swinging.

Where his predecessor, retired Sen. Jon Kyl of Arizona, was more of a behind-the-scenes, press-shy player, Cornyn sees the minority whip job as a role he needs to play in both public and private.

In preparing to take over the No. 2 GOP leadership spot, he visited with former Whips Kyl, Don Nickles of Oklahoma and Trent Lott of Mississippi.

And he’s been reading up on the position. Along with consulting “a lot of books about Senate leadership over time and Senate history,” Cornyn said he has also talked with Martin Gold, senior counsel at Covington & Burling, who served as floor adviser and counsel to former Senate Majority Leader Bill Frist of Tennessee.

“Now I think we are ready to hit the ground running, and when we get back, I think we’ll be ready to go,” Cornyn said in an interview with CQ Roll Call last week.

And that is just what he’s done. One day after officially starting the whip job, Cornyn took a hard line on the coming debt limit debate, telling the Houston Chronicle that a partial government shutdown may be necessary if the GOP is intent on squeezing more spending cuts out of President Barack Obama. Not long after that, Cornyn became one of the most outspoken Republican opponents of Obama’s nomination of former Nebraska GOP Sen. Chuck Hagel to be Defense secretary.

Spending cuts, Cornyn said, were a key element that was missing in the New Year’s Day fiscal cliff deal to avert tax increases and automatic spending cuts.

Cornyn also called for using the automatic spending cuts — known as the sequester, which was delayed until March 1 under the cliff deal — and the expiration of a stopgap spending bill — known as the continuing resolution — as leverage to force to Obama to the negotiating table.

“I see this is our next opportunity — the combination of the sequester, the expiring continuing resolution and the debt ceiling — and I think we ought to use the leverage that we have to get the president to the table because I don’t think that he will ever voluntarily produce Medicare and Social Security reforms even though he understands the problem better than anybody,” Cornyn said.

The president has vowed not to negotiate on the debt ceiling, citing concern about repeated showdowns on the issue. Failure to raise the debt ceiling or partly shutting down the government would needlessly damage the economy, Obama has said. But Cornyn argued that the president is using scare tactics to avoid engaging with Republicans.

“The president wants to sound like Chicken Little and say the sky is going to fall if we delay payment on some of our bills for a few days or a week while we negotiate very important spending cuts,” Cornyn said.

He added: “We expect to get an outcome, and we expect to get one that involves reining in spending. … It is not going to include any revenue. We are done with that. The president got the revenue he extracted in the [fiscal cliff] vote, but we are done with that, and now it’s going to be about reining in out-of-control spending.”

Cornyn also said he believes Hagel will not be confirmed as secretary of Defense. “I felt very strongly that he was the wrong person for that job, even though I have a lot of respect for Sen. Hagel personally. But this is not about personalities or politics, this is about national security policies that I believe he is profoundly wrong on.”

“I don’t know how you remake yourself after you basically said you could live with an Iranian nuclear weapon, advocated direct talks with terrorist organizations like Hamas and where I worry that he would preside over the decline in American leadership and national security power at the Pentagon,” Cornyn said. “So I think his record is well-known. … I think the record is pretty clear, so I think there is a very good chance that he won’t be confirmed.”

He declined to say whether he would filibuster Hagel’s nomination.

Lest anyone think Cornyn is freelancing, he said he discussed his decision to speak out on the debt limit and on Hagel with Senate Minority Leader Mitch McConnell of Kentucky. “My job is not to surprise the leader. … My job is to support him and provide him the assistance he needs from the whip’s office,” Cornyn said.

McConnell spokesman Don Stewart agreed that the two are working closely together. “The leader and the whip are in constant contact. The goal of the whip is to help the leader, and Cornyn has been great since he’s been on the job,” Stewart said.

Cornyn has an opportunity to take the role of chief messenger for the party in the Senate, given the relative shortcomings of McConnell and other Senate GOP leaders when it comes to public appearances and interviews. One Senate GOP aide noted that Cornyn’s “media savvy” will likely come in handy as the GOP battles the president on a number of fronts this year.

As for the other parts of the job, Cornyn said his stint as chairman of the National Republican Senatorial Committee will help him understand the political pressures GOP senators may feel on certain votes. He said he plans to work even more closely “with all the members of the conference because [as whip] you need to understand where they are coming from, where their concerns are, where they need more information.”

He stressed that, like McConnell, he would take a hard line on the ability of the minority to offer amendments to legislation, which Republicans believe has been hampered under Democratic rule.