United States Senator Jeff Flake (R-Arizona) is interviewed by the local media after a community water forum at the Arizona State University downtown campus in Phoenix, ArizonaTuesday April 7, 2015. (Laura Segall/for The Washington Post)

When Jeff Flake led a congressional delegation to Cuba nine years ago, he came, as is the custom, bearing gifts for his Communist hosts. But instead of a plaque or trinket, Flake brought copies of “The Wealth of Nations,” Adam Smith’s seminal economic treatise, and “Free to Choose,” Milton Friedman’s paean to capitalism.

The gospel of free markets has yet to transform Cuba, but Flake will be in Havana on Friday to witness a milestone he has long advocated during his nearly 15 years in Congress: the reopening of the U.S. embassy and the formal end of a 54-year diplomatic freeze.

“It’s going to be quite a moment,” said Flake, who has visited Cuba a dozen times, adding, “I wish there were some other Republicans.”

That the junior senator from Arizona will be the only Republican lawmaker in the American delegation accompanying Secretary of State John F. Kerry is the latest reminder of Flake’s unusual willingness to chart his own path on some of the nation’s most divisive issues.

On a range of matters — Cuban relations, nuclear negotiations with Iran and immigration policy, to name a few — Flake has found himself more closely aligned with President Obama than conservatives in his own party.

Flake says he abides by advice he got upon arriving in the House in 2001: “If you vote consistent enough, then when there’s a vote people don’t understand, they’ll give you the benefit of the doubt.”

In his six House terms, Flake has carved out a distinct profile as a spending hawk willing to take on anyone — including his own party’s leadership — to curb federal profligacy. When Congress banned spending earmarks in 2010, he could rightly claim to have actually changed Washington.

“A true conservative, Flake is as rare as the dodo,” Esquire wrote in 2008. The Weekly Standard in 2011 called him “a tea partier before there were tea partiers.”

In the years since, the party orthodoxy on spending has only moved closer to Flake. But on other issues, Flake has stuck to his free-market, often libertarian principles even as the party has hardened around other positions, and conservative activists aren’t giving him the benefit of the doubt.

In the 2012 race for the seat he now holds, he won the endorsement of the Senate Conservatives Fund, a group established by then-Sen. Jim DeMint (R-S.C.) to elect more rock-ribbed candidates.

Now the same group is threatening to support a primary challenger three years before Flake is up for reelection. Ken Cuccinelli II, the fund’s president, said in a statement that Flake has been “an embarrassment” to conservatives.

“Whether it’s supporting amnesty, gun control, Obamacare funding, or the president’s failed foreign policy, Senator Flake has betrayed the voters who sent him to Washington and should be replaced with a true conservative in 2018,” Cuccinelli said in a statement.

Conservative darling to scourge

Flake does not seem particularly shaken by his transformation from conservative darling to scourge. In a series of interviews this year, he said he remains determined to follow his own path.

“Life’s too short,” he said this week. “Certainly my political life is too short to worry about these kinds of things. I would not serve my constituents well by being in lockstep with the party. I wouldn’t be able to justify the time it takes away from my family and everything else if I were just go-along-to-get-along.”

On spending issues, Flake remains doctrinaire. On the 2016 federal budget, he opposed every amendment that would have hiked spending. He was one of only three senators — joining Mike Lee (R-Utah) and Jeff Sessions (R-Ala.) — to vote against an amendment opposing Medicaid benefit cuts.

He holds stellar ratings from the Club for Growth and the National Taxpayers Union. And he has maintained a sharp focus on government waste, highlighting government programs he’d cut in social-media-friendly packages like his recent “Jurassic Pork” report or his March Madness-themed “Egregious Eight Tournament of Waste.”

But with the congressional appropriations process again stalled, Flake has found it difficult to be the kind of spending hawk he was in the House, digging into programs, line item by line item.

At a Rotary Club luncheon in Sedona in March, Flake described how he made enemies in his own party by calling out earmarkers on the House floor and how a succession of pay-to-play scandals finally led to their demise.

“There’s still a ban on earmarks in Congress, and that’s a good thing,” Flake declared to applause.

But explaining his conservative bona fides these days requires elaborating on the federal budgetary process — detailing the demise of “regular order” and the rise of the continuing resolution and the last-minute omnibus spending bill.

That has left conservative activists to dwell on his more recent positions: His support for comprehensive immigration reform, including the bipartisan Gang of Eight talks; his backing of Obama’s nuclear negotiations with Iran; and his vote to confirm Loretta Lynch as attorney general.

“There is something that’s fundamentally changed since he’s been in the Senate,” said Dwight Kadar, a retired businessman and Republican activist who came to the Rotary luncheon with a “Don’t Tread on Me” pin on his jacket. “In fact, I told him . . . ‘I don’t recognize you anymore. I don’t think you’re really representing Northern Arizona and its values.’ ”

The ‘anti-Ted Cruz’

Flake, 52, and those who know him best insist he hasn’t changed much at all since succeeding former senator Jon Kyl (R). But his unorthodox positions have become a lot harder for conservatives to overlook. That has proved doubly true as Senate classmate Ted Cruz (R-Tex.) gained a prominent national profile through his hard-line opposition to Obama.

Instead, Flake has tried to forge a different kind of conservative identity — one more focused on a long-term strategy of reining in the federal government rather than winning the next Republican primary.

“He’s sort of the anti-Ted Cruz,” said Clint Bolick, vice president for litigation of the Phoenix-based Goldwater Institute, a free-market think tank Flake once led. “He doesn’t seem to be consumed by ambition. He’d like to get some things done, and this is the right place and the right time.”

Flake says he’s itching to move beyond spotlighting wasteful programs to “play a role in the big deal, the grand bargain, if you will” — referring to the elusive prospect of a bipartisan solution to rein in the national debt.

But what Flake has witnessed so far in the Senate has disappointed him. His dimmest day in Congress, he says, was when his colleagues killed, 95-3, a provision in the 2013 Ryan-Murray budget deal that would have slightly reduced the annual cost-of-living adjustment for younger military retirees, saving the government $6 billion.

“I thought, if we can’t stand the pressure that comes from a small group like that, how are you ever going to stand up to the broader groups?” he said.

Flake is now playing a more visible role in foreign affairs, his other area of political passion dating back to his days as a young Mormon missionary in South Africa and pro-democracy activist in neighboring Namibia. There, he grew skeptical of American efforts to wall off nations politically and economically in hopes of changing their policies.

On Cuba, “he’s helped many other Republicans to take a second look at the issue, that we don’t need a separate foreign policy on Cuba when we have trade with, diplomatic relations with . . . many other countries we disagree with on human rights issues,” said Phil Peters, a former State Department official who runs the nonpartisan Cuba Research Center and has accompanied Flake on several of his dozen trips there.

And Flake’s thinking on the Iran deal is being watched intensely given that his support could give Obama’s efforts at least a patina of bipartisanship.

In remarks on the Senate floor last week, Flake said he remains undecided and that he could still be convinced to vote in support if he were more thoroughly assured that the U.S. would retain the ability to reimpose sanctions on Iran for supporting “nefarious non-nuclear activities.”

That position is considerably more nuanced than the defiant line held by most congressional Republicans, and even the possibility that Flake might support the deal has outraged conservatives.

Support in Arizona

Flake retains strong support in the Arizona business community; holds an enviable political base in the northeastern part of the state, where the Flake family settled in 1878; and, like fellow Arizona Republican John McCain, is hoping his maverick streak works in his favor.

“He didn’t come to Washington without a clue of what he was doing; he went out there purposely to change things and take on the establishment, and I think that really resonates for people here,” said Brian Murray, an Arizona political consultant who advised Flake’s 2012 campaign.

Bolick says Flake is the “ideological heir” to his group’s namesake, five-term senator Barry Goldwater. “By and large, it is the right fit for Arizona.”

To burnish his profile back home, Flake has staked out a role on the particularly Arizonan issues of fire, water and land management. Still, his refusal to stay in an ideological box has caused him political fits.

Social conservatives blasted Flake’s 2013 votes for the Employment Non-Discrimination Act and to allow gays and lesbians to serve openly in the military. Liberals and moderates blasted his opposition that year to more stringent federal background checks for gun buyers, and his immigration stance seems to have pleased no one at all.

When Flake announced earlier this year that, with comprehensive reform faltering, he was co-sponsoring a bill that would toughen border security without addressing undocumented residents already in the U.S., an Arizona Republic editorial declared him “part of the immigration problem.”

More recently, he has co-authored a bill to crack down on so-called “sanctuary cities.” But he has broken with GOP colleagues, including Cruz, who want mandatory prison terms for aliens who re-enter the country illegally after being deported.

Flake acknowledges enjoying the luxury of his principles in a non-election cycle: “There are a lot of good things about the Senate,” he told a gathering of local officials in Sedona. “But nothing better than a six-year term. Don’t let anyone tell you otherwise.”