Jeb Bush announced his exploratory PAC in mid-December, and led most Republican polls for the next month. In late January, Scott Walker wowed the audience at the Iowa Freedom Summit, and rivaled or surpassed Bush in polls for the two months that followed. This month, Marco Rubio declared his candidacy; two brand new polls now show him on top.

Is this a high-speed version of the 2012 primary season, in which nearly every dog had his day, but then got unceremoniously packed off to the pound? Are Bush and Walker toast?

Nope: there’s something to admire in each of the major Republican candidates, but the two more prominent governors are still likely to be the frontrunners. Furthermore, Walker has an edge when you consider how Republican voters see the world today. Their concern is that President Obama has not merely adopted harmful policies that any Republican can reverse, but that he has put big government and American retreat on autopilot.

They have a point. Economically, there are long-term consequences to making policy based on views like Obama’s assertion that, “If you’ve got a business, you didn’t build that,” and Hillary Clinton’s admonition that, “don’t let anyone tell that, ah, you know, it’s corporations and businesses that create jobs.” The consequences include a workforce participation rate that has declined during the Obama era to only 63 percent — the lowest since Jimmy Carter was president. Federal debt now tops $18 trillion, income tax rates are higher than any time since the Carter era, and the economy is being kept barely afloat by a drunken-sailor monetary expansion whose ultimate consequences are unknown but likely perilous. None of this will be remedied easily.

At home and abroad, the security picture is equally bad. The next president will face a faltering war against ISIS, radical Islam on an unchecked rampage, and newly confident adversaries like Iran, Russia, and China in expansionist moods. Confronting these threats will require effective tools of statecraft and allies willing to cooperate. But Obama has hollowed out the military and destroyed our traditional allies’ confidence in us — problems that will take more than just soothing words to fix.

Socially, Obama has undermined the bedrock of our culture. Americans worked hard to make their country the greatest multicultural society since ancient Rome, largely by getting better at ignoring skin color and gender and instead judging people by the content of their character. But this president, who was supposed to usher in a “post-racial” America, has instigated the most racially obsessed period in decades. Thinly evidenced accusations that racism and sexism pervade our society have become an addictive weapon for liberals. Far from being a passing trend, our next generation is being indoctrinated at universities with the view that our nation is corrupt and evil, and that victimhood trumps merit. Today’s liberals are already planting the seeds of tomorrow’s liberals. Democrats and even some Republicans hope to swell their ranks further still with millions of illegal aliens.

Why is Scott Walker better suited than other Republicans not simply to oppose, but actually reverse these trends? Three reasons:

First, Walker is undeniably effective. In his first term alone, he enacted laws that reduced government spending, cut property and income taxes, turned a budget deficit into a surplus, required a supermajority for any future income or sales tax increase, recognized law-abiding citizens’ right to carry concealed weapons, required a photo ID to vote, and reformed state government.

Second, Walker knows how to interrupt the cycles that liberals use to perpetuate the growth of government. In 2011, he signed legislation that limited government employees’ unsustainable benefits and union privileges. The move balanced the budget and stopped forced payroll deductions that unions used to lobby for ever-bigger government. This year, Walker extended reforms to the private sector by signing right-to-work legislation that prevents forced unionism. He has also sought reform at state universities that provide an academic elite with cushy lifetime jobs while saddling students with crushing debt and decreasingly useful degrees.

Third, Walker is temperamentally suited to win office and force real change. It’s one thing to be a conservative politician in a conservative state. But Walker has achieved massive reform in a state that historically was a stronghold of the other party. His 2011 fight to disempower the government unions caused perhaps the biggest political freak out so far this century. Walker stood his ground with quiet confidence and effective, disciplined communications. How many senior-level officials in today’s GOP would have done the same?

Those personal traits also enabled Walker to prevail in three gubernatorial elections, including a recall election in which the unions and national Democrats threw everything they had at him. Voters see in Walker a calm authenticity and an alternative to the hackneyed rhetoric and identity politics of recent years. He is disciplined and appeals to more than just Republicans.

In this election, the mainstream media — always subconsciously eager to remain the palace eunuchs in the Democrats’ Forbidden City — will back Hillary or whomever the Democrats nominate. Should a Republican win the White House, the shrill cries over the miniscule “sequestration” cuts to domestic spending in 2013 will be but a mild preview of what’s to come. The Obama legacy and these challenges are why many Republicans want to nominate an experienced governor to run — preferably one with a revolutionary flair and serious political skill.

Put simply, if you want to win a revolution, wouldn’t it be handy to have a leader who has already won one? Scott Walker did — deep in what used to be liberal territory.

Christian Whiton was a State Department senior advisor during the George W. Bush administration. He held policy positions in the Giuliani and Gingrich campaigns, and is the author of “Smart Power: Between Diplomacy and War.”