U.S. Sen. Johnny Isakson said Thursday his goal is lower tax rates applied against a higher tax base — but the drop people are seeing in their take-home pay this month isn’t part of that equation. 

The smaller checks are due to the expiration of a temporary 2 percent payroll tax holiday aimed at stimulating consumer spending and the economy.

Isakson voted against the 2012 extension that kept it a second year, and he was sympathetic but unapologetic during a Rome Rotary Club Q-and-A session.

“You need to make your contributions to Social Security, for your retirement,” he told the unprecedented crowd of more than 120 who showed up for the club’s monthly lunch at Coosa Country Club.

“You’ve got to pay your bills,” he continued. “This isn’t an increase in the tax rate. It’s a return to what the rate was.”

Isakson spent much of his time talking about Congress’ ongoing battle to address a national debt that’s roughly equal to the gross domestic product.

He said “debt is not necessarily evil,” but the country should not be leveraging more than 80 percent of its GDP. His twofold approach: stop spending more than is taken in, and empower the private sector — which will increase the GDP.

Cuts have to include benefits and entitlements, he said, but adjusting eligibility formulas could ultimately save and strengthen programs such as Social Security and Medicare.

“You paid for it. You deserve to have it,” he told the group.

Asked for his thoughts on President Obama’s cabinet picks, he unhesitatingly praised Sen. John Kerry, D-Mass.

“He is qualified to be secretary of state,” Isakson said.

The two recently co-sponsored legislation bolstering the State Department Rewards for Justice program, which targets people such as Lord’s Resistance Army leader Joseph Kony who are accused of terrorism, narcotics trafficking or war crimes.

But Isakson said he’s withholding support for the nomination of Obama counterterrorism advisor John Brennan as CIA director.

“I’m not going to vote for anyone involved in the Benghazi deal until we get some answers,” he insisted, referencing the Sept. 11, 2012, attack on the U.S. Consulate in Libya.

And he later said he has “serious concerns” about former Republican Sen. Chuck Hagel as defense secretary. Hagel has been accused of being tough on Israel and soft on Iran.

“Israel is our best partner in a very bad part of the world,” Isakson said, adding that even Hagel’s older statements count as indications of his overall attitude toward the country.

Questioned about gun control, Isakson said he is working on a mental health registry he contends would be far more effective at halting mass shootings than any weapon ban.