CEDAR RAPIDS, IOWA — Is Rand Paul still running for president? Or has he officially decided he's just a message candidate?

And his message: Marco Rubio is dangerous, because he's wrong about privacy, national security and war.

Follow Paul's speeches and answers to questions, and you'll see the theme.

"If Marco gets elected," Paul told me Friday when I asked him his strategy for the Islamic State, "he'll bomb the heck out of ISIS, and you'll get it all rising back up in a decade." I didn't mention Rubio in my question or previously. Paul did.

If it's about spending, it's about Rubio: "I ask Sen. Rubio," Paul said on stage today at FreedomWorks' Rising Tide Summit, "is it conservative to add a Trillion dollars to the national debt? He says it's for the military." Rubio was the only Republican opponent Paul criticized in Cedar Rapids, either in his press conference or in his speech.

Asked about domestic surveillance in the context of the California shooting, Paul pivoted to Marco: "Those who clamor to give up our liberty for a false sense of security really aren't paying any attention. Senator Rubio has been out there saying, 'Oh we need to spy on Americans, we need to collect all Americans' records.' But we have been, and it hasn't worked."

Immigration question? Rand attacks Rubio: "This is a big difference I have with Marco Rubio," Paul began his answer at a press conference here today. "To defend the country, Marco Rubio wants to collect all your records and invade your privacy. I want to say let's have" some border control.

That makes some sense. There's plenty of reason to believe Rubio is really the front-runner in this race. Many pundits, including me, believe Trump's and Carson's support are illusionary. That leaves Marco as the top dog, and it's rational to target him.

But if you drill deeper into strategy, does Paul really think he's competing with Rubio for voters? Tim Alberta of National Review asked Paul if he was concerned that he was losing "liberty voters" to Ted Cruz. This was a good question, and Cruz is probably the biggest threat to Paul's support. Paul's answer on the Cruz question: "I'm more concerned with Marco Rubio."

Why? "There's not a dime's worth of difference between Marco Rubio and Hillary Clinton on foreign policy. They've been dead wrong for the past decade, and they have endangered their country."

This sounds more like a guy who's running against Rubio's foreign policy than like a guy who's trying to win the nomination.

Another Paul answer sounded similar:

"If you want to give up all of your privacy, I'm not your guy — I'm the wrong candidate. But I think there needs to be somebody in the race who does want to defend the 4th Amendment."

Again: "I think there needs to be somebody in the race who does want to defend the 4th Amendment."

There is a long history of message candidates in presidential primaries. Lawrence Lessig was a message candidate in the Democratic field, trying to push the idea of campaign finance restriction. Ironically, the most straightforward message candidate in this year's election was Lindsey Graham, whose message was "Rand Paul is wrong on national security."

Today Paul, in the low single-digits in Iowa and New Hampshire polls, may be running not for president, but for the opportunity to warn Americans that Marco Rubio and Hillary Clinton are wrong on national security.

Timothy P. Carney, The Washington Examiner's senior political columnist, can be contacted at tcarney@washingtonexaminer.com. His column appears Tuesday and Thursday nights on washingtonexaminer.com.