“I am suspending my race for the presidency,” Mark Sanford, who you might have not known was running, ­announced Wednesday — “because impeachment has made my goal of making the debt, deficit and spending issue a part of this presidential debate impossible right now.”

To which one might respond: What’s impeachment got to do with it?

Quid pro quo or no, President Trump’s Republican Party, in marked contrast to the scrappy GOP opposition under President Barack Obama, has not as a matter of policy or even rhetoric cared one whit about limiting federal debt, deficits or spending.

The debt clock crossed over the $23 trillion threshold on Halloween with nary a Republican peep. Remember how GOP backbenchers used to threaten government shutdowns if increases in the national borrowing limit weren’t tethered to spending cuts? Now they just join forces with House Speaker Nancy Pelosi and waive the debt ceiling away.

Trillion-dollar budget deficits were a rallying cry at Tea Party protests during Obama’s first term. Now those streets are empty as the annual gap between expenditure and revenue has stretched back up to $984 billion in this just-completed fiscal year, thanks largely to an 8 percent spending increase against a 4 percent boost in tax revenue.

Ten years ago, then-President-elect Obama warned about ­Social Security and Medicare, “What we have done is kicked this can down the road. We are now at the end of the road and are not in a position to kick it any further.”

The big difference now, aside from the additional decade of actuarial degradation, is that no politician even talks about it anymore. From 1997 to 2013, every State of the Union Address included at least some verbiage about fixing long-term entitlements. None have since.

The economists over at the Congressional Budget Office and Government Accountability Office are still cranking out budgetary death porn, such as: “Projected federal spending will ­increase more rapidly than revenue. Absent action to address this imbalance, the federal government faces an unsustainable growth in debt.”

But it is unclear whether there is any market for such gloom. “What’s needed here is simply a national conversation on whether or not we believe in math,” Sanford says, and he isn’t wrong. Yet he and other Republican debt and deficit hawks now find themselves utterly marginalized from their party’s profligate mainstream.

It is both easy and necessary to blame some of the public disinterest on Republican shamelessness. For instance, when Mick Mulvaney was still a member of the fiscally rectitudinous House Freedom Caucus in March 2015, he wrote that “there is no honest way to justify not paying for spending, no matter how often my fellow Republicans try.” By 2018, as arguably the most powerful member of Trump’s cabinet, Mulvaney had changed his tune to: “We need to have new deficits.”

But at least he once knew better. Sen. Bernie Sanders, in whose policy image Democrats have spent the last four years remaking themselves, has been wrong his whole career about government spending and economic intervention. And yet Bernie’s magical thinking about math has become the rage even in academia, where Modern Monetary Theory has essentially handed Democrats a blank checkbook.

And oh Lordy, are they scribbling in the zeroes.

The ballyhooed Medicare for All plan from Sen. Elizabeth Warren would cost $20 trillion in new government spending by her own estimates, which means you can safely double it.

Sen. Kamala Harris wants $2 trillion just for historically black colleges and universities. A trillion here, a trillion there — pretty soon it adds up to real money!

Then again, maybe all these politicos know something we hawks are reluctant to admit. Namely, that you win elections by promising voters what they want to hear. Trump routed the GOP field four years ago while mocking the green-eyeshade likes of Paul Ryan. Bernie’s democratic socialism resonated way more with millennials than the insincere class warfare of Goldman Sachs lecturer Hillary Clinton did.

What’s more, after nearly a full decade of low interest rates, low inflation and a steadily growing economy, the horror stories that deficit hawks like to tell have lost their ability to spook. Money is cheap until the moment it’s not; in the meantime, why not go shopping?

Having one major party at least rhetorically committed to fiscal sanity, with the other at least sporadically impelled to acknowledge math, looks in retrospect like a golden era. With both parties now unmoored, be very afraid of what happens when the music stops.

Matt Welch is editor-at-large of Reason. Twitter: @MattWelch