During the heyday of the tea party, libertarians and conservatives had little to quibble about. At its core, the tea party was a revolt against big- government liberalism. Whether one favored practically no government or one preferred modest government there was a common cause in opposing the stimulus, Dodd-Frank, Obamacare and cap and trade.

Sen. Marco Rubio (R-Fla.) (Joe Raedle/Getty Images
Sen. Marco Rubio (R-Fla.) (Joe Raedle/Getty Images)

However, as the debate has shifted to foreign policy and to domestic reform — not elimination of government — those differences have become more pronounced. In an interview toda,y Sen. Marco Rubio (R-Fla.) put it this way: “At its core, conservatism is not an anti-government movement, and it’s not a no-government. The conservative movement is about government playing its important yet limited role, and about not falling into the trap of believing that every problem has an exclusive government answer for it.” Conservatives want to use their own policy ideas to combat poverty, reform entitlements and improve schools, as well as provide an Obamacare alternative that, for example, protects those with preexisting conditions.

Rep. Paul Ryan (R-Wis.) is another potential 2016 candidate who is clearly in the reform conservatism camp. Salina Zito observes:

In the Longworth House Office Building, two miles across town from Woodson’s K Street office, Ryan talked candidly about his goal of learning what works in combating poverty and how government decisions affect people.

Known for fiscal pragmatism, Ryan has his eye on chairing the powerful Ways and Means Committee. That would compound his reputation as a serious policy intellectual and potential GOP presidential candidate. In recent speeches, Ryan’s message has turned populist; these visits outside of Washington have helped shape his view of life in America. . . .

His critics say Ryan’s zeal for championing the poor is pretense because he consistently suggests cutting entitlement programs. Democrats have attacked him with television ads in which an actor portraying Ryan throws “Grandma” over a cliff to demonstrate how his budgeting would hurt senior citizens.

The House Republican fiscal year 2015 budget resolution that Ryan authored in April, “The Path to Prosperity,” would cut spending by $5.1 trillion over 10 years.

‘This budget applies the lessons of welfare reform to other federal-aid programs,’ he wrote. He suggested enlisting states to root out waste, fraud and abuse. His plan “empowers recipients to get off the aid rolls and back on the payroll,” he wrote.

Ryan has carved out a complex political position with the emphasis on fiscal discipline and poverty, said Catherine Wilson, an associate professor of public. “Transcending party lines, this position makes a case for fiscal constraint and for attention to vulnerable communities,” she said. Ryan’s opinions might not activate the traditional Republican Party base, she said, but could attract the growing number of independent voters.

In fact, Ryan is where most conservatives are — fiscally sober but intent on making the government we do have effective, limited and vigorous. There really is no contradiction between wanting to restrict the size of government (e.g. cut out crony handouts, send some functions to the states, cut out the Obamacare bureaucracy in favor of a voucher for self-insured people) and make it more attentive to the needs of the poor. In fact, the latter is greatly harmed by a number of big-government restraints, including interference with school choice, entitlements that tip government payments to better off Americans, elimination of  excessive regulatory controls that harm employment and the debt-encouraging student loan system.

In domestic policy, conservatives believe that government still has a role in education, health care and more — but not necessarily at the federal level and with policies that limit bureaucracies and promote socially responsible behavior. You can see the difference between conservatives and libertarians in small, highly publicized  issues such as drug laws, but more than anything you see it in the choice of topics and the attitude toward government. Libertarians talk as if the government is the primary enemy — spying, persecuting and squashing liberty. Conservatives are wary, especially in the Obama era, of these tendencies, but the alternative they see to giant and oppressive government is not no government but smaller, leaner and more effective government.

That’s been the basis of the reform conservative movement. Yuval Levin, one of the movement’s architects, writes:

For conservatives, the role of government is to enable and sustain markets and other arenas of common action, ensuring competition, aiding the development of physical infrastructure and human capital, protecting consumers and citizens, and allowing the poor and vulnerable to participate along with everyone else. In practice, this means avoiding centralized programs that impose wholesale solutions from above in favor of those that enable a bottom-up, incremental, continuous learning process.

The conservative reform agenda aims to replace a failing liberal welfare state with a lean and responsive 21st century government worthy of a free, diverse, and innovative society. The following chapters are an attempt to show what such a government might look like, and how it could help the poor to rise, lift burdens off the shoulders of working families, end cronyism and special privileges for those at the top, and prepare America to flourish again.

In short, as libertarians and conservatives tell you what they are for as opposed to what they are against (the Obama agenda), the differences become more acute. But to be clear, libertarians’ alliance with conservatives makes infinitely more sense than with liberals. Conservatives are at least aiming for smaller government, control of debt and other measures that will result in diminishing the size of government, a positive step for libertarians.

The most glaring difference between libertarians and conservatives these days is certainly on foreign policy. After Sen. Rand Paul (R-Ky.) deleted a recommended book list featuring libertarian conspiracy theories and Pat Buchanan’s musings, former ambassador to the United Nations John Bolton observed, “This list embodies the continuing conflict between Sen. Paul’s prior professed beliefs and his current political ambitions.” Put differently, it embodies the difference between what will fly in libertarian (and extreme right-wing) circles and what is acceptable to mainstream conservatives. The silver lining to Obama’s disastrous foreign policy of retreat, reduction (in defense spending) and retrenchment is that he has reminded the GOP of its historic role as the party of national security and of human rights, about which most libertarians are entirely unconcerned as a policy matter.

If the GOP is to recapture the White House, it won’t because millennials are afraid the government is listening to phone calls or because they want drug legalization. It will be because conservatives have rekindled a domestic reform agenda and a responsible national security policy around which the country as a whole can rally. The only path to victory — if you do the math — is through a center-right agenda that sweeps in and invigorates conservatives, independents and some moderate Democrats. It’s those voters who want a government that functions better. For libertarians that should be preferable to eight years of Hillary Clinton, if in fact she wants to face her foreign policy record head-on.

Jennifer Rubin writes the Right Turn blog for The Post, offering reported opinion from a conservative perspective.