For a moment, Rand Paul gets back to his basics

Sen. Rand Paul
Getty Images
Sen. Rand Paul

CHICAGO — Having spent last week filibustering the Patriot Act in the Senate, then blaming Republican war hawks earlier in the day for the rise of the Islamic State terror group, Sen. Rand Paul took a break from incensing his own side on foreign policy to talk about the American economy.

It was not that long ago that the question was whether Paul, an ophthalmologist who won his Senate seat in 2010 on a wave of fiscal-minded tea party support, would have enough to say about national security in a 2016 presidential race.

That question has surely now been answered, begging a new question: Does he have too much to say on the subject for his own good?

One Paul campaign insider told CNBC.com that the Kentucky senator's latest feat of noninterventionist, data-privacy evangelism, and the resultant backlash he's attracted from neocons and other GOP presidential prospects was all playing to Paul's political benefit. Thus, there was no desire to change the subject anytime soon.

Read More Sen. Rand Paul ends Patriot Act 'filibuster'

But a scheduled trip to the heartland, planned in conjunction with the release of Paul's political autobiography, "Taking a Stand," has necessarily shifted some of Paul's focus for at least a few days.

It has also given Paul's campaign an early opportunity to reflect on which leg of the libertarian stool it will try to lean most heavily on going forward: foreign or domestic.

And while the campaign and candidate seem to be relishing the senator's current role as Edward Snowden's man in Washington, others argue that Paul's best bet for the presidency is to refocus, sooner than later, on fiscal conservatism.

"The fiscal side of the thing is more important for him to succeed because he needs something to resonate with both the base and the mainstream American voter," said Jonathan Bydlak, who was director of fundraising for Ron Paul's 2008 presidential campaign and is president of the Coalition to Reduce Spending.

"I don't necessarily view it as issues of foreign policy versus domestic," said Steve Grubbs, Paul's chief Iowa campaign strategist. "Rand has said from the beginning that he wants to build a campaign and bring together people who supported his father and grow that coalition of nontraditional Republican voters."

Read More In U.S. cities, Republicans look for a few good losers

Sure enough, as Washington spent Wednesday fussing over Rand Paul's crack-of-dawn jab at Republican neocons—on MSNBC's "Morning Joe" ("ISIS exists and grew stronger because of the hawks in our party who gave arms indiscriminately"), Paul was back to his basics, chatting about lowering taxes and shrinking government spending.

As he has done over the last year, Paul brought this message Wednesday to a traditionally Democratic audience—a crowd of largely black and Latino residents on Chicago's South Side, right in President Barack Obama's back yard.

Paul was visiting here at the invitation of Pastor Corey Brooks, minister of a black church in the neighborhood, who had previously hosted and later endorsed another Republican, Illinois Gov. Bruce Rauner. (Paul's campaign manager Chip Englander managed Rauner's successful campaign.)

Speaking from a stage in a parking lot across the street from Brooks' New Beginnings Church, Paul told onlookers that if they were looking for government to solve their problems, they ought to heed the words of Malcolm X: "Nobody can give you freedom, nobody can give you equality, nobody can give you justice; If you're a man, you take it."

In addition to advocating for school choice and reduced minimum sentences for drug offenders, Paul spoke about his idea to create "economic freedom zones," an eligibility standard for poor neighborhoods to receive additional tax breaks. Paul said his plan, which he adopted from former Sen. Jack Kemp, would create $400 million a year in tax breaks for Chicago's South Side alone.

Later, during a Q&A at Chicago's Merchandise Mart, hosted by the free-market Illinois Policy Institute, Paul announced that he would be unveiling his presidential tax reform platform in the next few weeks. Paul has previously said he would like to create a flat tax for individuals and businesses around 17 percent.

When an audience member asked which federal agency or governmental department he would most like to do away with, Paul neatly quipped, "I thought this would be an easier question: Name the department you would want to keep." (He then put the Commerce Department on notice.)

On Thursday, the Kentucky senator heads to the key early state of Iowa, where he has already spent a lot of time, and where the latest polls show Paul running in the thick of a pack that trails front-runner Scott Walker, the Wisconsin governor.

Among other things, Paul is slated to discuss his plans for ethanol deregulation, a subject near and dear to the state's economic interests. Paul has previously co-sponsored a bill with Iowa Sen. Chuck Grassley, the Fuel Choice and Deregulation Act, which would protect certain ethanol-containing fuel from EPA restrictions.

"The traditional paradigm of ethanol in Iowa is you either support an ethanol mandate, or you don't," said Grubbs. "Rand Paul did his best Captain Kirk and said, there has to be a third way."