If Jeb Bush has sought to campaign for president as, in his own words, a “joyful tortoise,” Rand Paul might be the Republican primary’s snapping turtle.

Earlier this year, Paul memorably appeared testy and impatient in an interview with NBC’s Savannah Guthrie. During the first Republican debate, he visibly rolled his eyes at Chris Christie during a discussion of national security. And last week, during a 24-hour livestream of his campaign, Paul seemed annoyed with the exercise, calling it a “dumbass livestream.”

At his campaign headquarters in Washington, D.C., on Thursday, the Kentucky senator had ample reason to be buoyant. CNBC had just confirmed this week that Paul would be among the Republicans on the prime-time stage Wednesday in Boulder, Colo., for the third GOP debate. And a few recent national polls have shown the libertarian’s anemic support on the rise, if only slightly.

But Paul was again in a foul mood. In particular, he did not want to discuss Ted Cruz, who has emerged as a key rival.

A question about Paul’s recent remark that Cruz is “done for” in the Senate after burning bridges with colleagues, which seemed to suggest that Paul still values legislative pragmatism in an election cycle that does not, was immediately a nonstarter.

“I don’t think your question is related to our message,” Paul said flatly. “Our message is one that we’re not using the power of the purse, that Republicans were elected to run the House and run the Senate, and we’re not using that leverage for anything.”

A follow-up to clarify, putting emphasis on how Paul would contrast his style in the Senate with Cruz’s, did no better.

“I guess I’m not interested in your line of questioning, so if that’s it, we’ll just stop,” Paul said. “I’m interested in having an interview, but I’m not interested in picking a fight with somebody.”

Except, perhaps, with the interviewer. Another question: Cruz has sought to attract libertarians, Paul’s natural base, so what does Cruz’s success say about the campaign Paul has run and his own appeal to libertarians?

“If this is what you want to do for your interview, if this is your goal, somehow to sort of have a contrast article with myself and Cruz, I’m just not interested,” Paul fumed. “So do you have anything you want to ask about what we’re doing or our campaign? Because I’ve got just another minute or two.”

We’d reached minute two of an interview scheduled for 15 minutes.

If Cruz has become an uncomfortable topic of conversation for Paul, it might be because the Texas senator’s strategy has seemed to doubly foil Paul’s own. First, Cruz has run proudly on a record of obstruction in the Senate; Paul, on the other hand, seems to have an affinity for the institution and to take pride in his relationships with colleagues. Second, Cruz has openly courted the libertarian wing of the GOP, apparently with some success — drawing from Paul’s most obvious base of support.

"I'm one of the original co-sponsors of Ron Paul's audit-the-Fed" legislation, Cruz recently told an Iowa audience, according to a Los Angeles Times report.

Paul’s campaign has seemed to acknowledge the budding rivalry. After Paul edged out Cruz to win the Republican Liberty Caucus straw poll in New Hampshire earlier this month, his campaign took this swipe in a press release: “Unlike Sen. Cruz, Rand Paul has consistently voted against raising spending and is the only candidate fighting to protect the entire Bill of Rights.”

As Paul looks to invigorate his campaign for president, that theme of fiscal conservatism will likely be at the center, including during the debate next week.

“I don’t think you can be a conservative and be liberal with spending money for the military,” Paul said. “I think that’s one of the contrasts I will try to draw, and it’s a contrast that I think is an important one, because every other candidate on the stage will be somebody who is actually a fiscal liberal when it comes to military spending.”

But he will need to make up significant ground if he is to continue to compete for the Republican nomination. During the most recent fundraising quarter, Paul’s campaign brought in just $2.5 million, to end September with $2.1 million in the bank. That haul was roughly one-third of what he raised during the previous quarter.

Meanwhile, he has continued to poll in the low single digits nationally and in the key early primary states.

In a memo to supporters last week, Paul’s chief strategist, Doug Stafford, insisted that Paul’s campaign is not “on the ropes,” but instead is well positioned for a “breakthrough.”

In his interview with RealClearPolitics, Paul said the voters who would be key to his success include college students, independents who diverge from traditional Republican views on foreign policy and national security, and libertarians.

“I think when you combine all three of those together … I think there is enough for us to win in Iowa,” Paul asserted. “We fully intend to win. Our goal is not placing, but winning.”

But Paul is not only facing pressure on the presidential campaign front: He is also running for re-election to the Senate, making him the sole senator to run for both offices simultaneously this year. (Marco Rubio, who also would have been up for re-election in 2016, decided not to seek another term; Ted Cruz and Lindsey Graham are not up for re-election this year.) A Politico story published Friday reported that National Republican Senatorial Committee officials have begun to pressure Paul and his campaign to put more focus on his re-election to the Senate.

Given his two lackluster campaigns and a grueling presidential stump schedule, Paul rarely looks like he’s having much fun.

Indeed, that recent livestream made news largely thanks to Paul’s grumpiness. During a segment wherein he answered frequently searched questions, Paul read one asking whether he is still running for president.

"I don't know, I wouldn't be doing this dumbass livestreaming if I weren't," he deadpanned. "Yes, I'm running for president. Get over it."

By Thursday, roughly one week after the livestream aired, Paul was clearly tired of talking about it.

“There are some people who have difficulty understanding what sarcasm is, and there’s also some people who are maybe simplistic-natured and they see things in a literal fashion,” Paul said. “And we meant it to be humor.”

He pointed out that his campaign had started selling livestream-themed T-shirts, and he said plans are in the works for “Dumbass Livestreaming, the sequel.”

It might have been the right time, then, to ask whether there is any joy left for Rand in campaigning for president. But that question seemed already to have been answered.

On the first floor of his campaign headquarters, a well-appointed row house on Capitol Hill, a wartime poster of Winston Churchill shouts to the viewer: “Deserve Victory!”

Churchill ruminated on the theme of victory in his first speech to Parliament as prime minister, famously saying that “without victory, there is no survival.”

Perhaps Rand Paul is just trying to survive.