House Republican leader John Boehner of Ohio, right, and Senate Minority Leader Mitch McConnell of Ky., left. (J. Scott Applewhite/AP)
Opinion writer

With Republican majorities in both houses, the new Congress should begin by focusing on traditional GOP priorities: improving the nation’s sagging infrastructure, reforming an unwieldy tax code and finding ways to boost middle-class opportunity.

When pigs fly, you say? Skepticism is definitely in order. But Senate Majority Leader Mitch McConnell and House Speaker John Boehner have a fundamental choice to make. They can acknowledge the obvious areas of common ground they share with President Obama — thus showing that the Republican Party can participate responsibly in government — or they can throw temper tantrums.

McConnell told The Post that one of his goals, as he takes leadership of the Senate, is to avoid doing anything that would make it harder for the party to elect a president next year. “I don’t want the American people to think that, if they add a Republican president to a Republican Congress, that’s going to be a scary outcome,” he said.

The scariness of the GOP field probably will also depend on Ted Cruz’s apocalyptic rhetoric and Chris Christie’s progress in anger management. But McConnell is right that the whole “Party of No” routine, which he helped orchestrate, is unlikely to yield further political benefit — and may, at this point, inflict more damage on Republicans than on Democrats.

It is perhaps inevitable that the GOP will use its control of Congress to highlight the party’s pet issues — advocacy for the Keystone XL pipeline, for example, and opposition to the Affordable Care Act. Every once in a while, Republicans may even muster the needed 60 votes in the Senate — and force Obama to use his veto. But then what? Passing a bunch of bills that have no chance of ever becoming law is not the best advertisement for effectiveness.

McConnell told The Post he wants voters to see his party as a “responsible, right-of-center, governing majority.” Well, two obvious things such a majority should be doing right now are celebrating the economic recovery and looking for ways to ensure that more of its benefits reach the middle class.

Growth is accelerating, inflation is virtually nonexistent, stocks had a great year, unemployment is down and the U.S. economy is the envy of the developed world. That all of this has happened under the leadership of a Democratic president may be inconvenient for GOP leaders, but it’s the reality. Sourpuss grousing about how Obama is somehow “killing jobs” sounds ridiculous and out of touch. It seems to me that a “responsible” majority ought to be able to bring itself to say, “Nice job, Mr. President.” Even if it hurts.

Such a majority then should recognize that present economic conditions offer the opportunity to address big structural problems — and that addressing these problems can, in turn, broaden and deepen the recovery.

Infrastructure is perhaps the most obvious place to begin. Our airports are getting old. Many of our seaports cannot handle the newest generation of container ships. Thousands of our bridges need to be repaired or replaced. Century-old municipal water systems are breaking down. The electrical grid needs to be more robust and secure. And while we invented the Internet, citizens of other countries enjoy networks with faster speeds and lower costs.

Republicans used to agree with Democrats that good economic times offer the opportunity to invest in infrastructure — which creates jobs, both now and in the future. Deficits are falling rapidly and interest rates are at historic lows. What are we waiting for? Shouldn’t a “responsible” Congress have a bill on Obama’s desk by the end of the month?

Another subject on which Obama and the Republicans in Congress agree, at least in principle, is the need for corporate tax reform. Obama has acknowledged, and Republicans have long contended, that the current top corporate rate of nearly 40 percent is too high — and that the strategies corporations use to avoid paying those taxes, such as moving their headquarters overseas, are detrimental to the national interest. There is a larger debate to be had about overall tax policy, but couldn’t we just start by lowering the corporate rate and closing the loopholes?

Finally, a “responsible” party that’s prepared to govern would have some ideas about how to boost economic mobility, which is what we really mean when we talk about “opportunity.” If Republicans think the American Dream means the rich getting richer and the poor getting poorer, then no, they’re not remotely ready for prime time.

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