Say what you will about Donald Trump pulling the United States out of the Iran deal. Personally, I wish the United States had stayed in. But this sort of zig-zag is exactly what happens when you end up governing with your pen and your phone, as Barack Obama did.

Faced with a recalcitrant, obstructionist Republican Congress that he helped bring to power two years into his presidency, Obama increasingly gave up on getting congressional approval for anything: military actions, immigration policy, trade policy, net neutrality, environmental regulations. Instead, as Damon Root wrote a few years back, Obama did exactly what he once had criticized his predecessor for and went full Andrew Jackson:

In December 2007 presidential candidate Barack Obama told The Boston Globe that if he won the 2008 election, he would enter the White House committed to rolling back the sort of overreaching executive power that had characterized the presidency of George W. Bush. "The President is not above the law," Obama insisted. Once elected, however, President Obama began to sing a different sort of tune. "We're not just going to be waiting for legislation," Obama announced. "I've got a pen and I've got a phone…and I can use that pen to sign executive orders and take executive actions and administrative actions."

Well, you live by the pen and you die by the pen, and so DACA, the Paris Accords, and the Iran deal (routinely described as "one of President Barack Obama's signature foreign policy achievements") are down the tubes.

If Obama had tried to negotiate the Iran deal as a treaty, rather than an agreement, he would have needed the Senate to sign off on it. Same thing with U.S. involvement in the Paris Accords and a bunch of other "signature achievements." He would almost have certainly gotten nowhere with a Republican opposition whose "top priority" was, according to "Cocaine Mitch" McConnell, making Obama "a one-term president." It would have taken extraordinary leadership, especially in the teeth of a recession and the wake of the one-party passage of Obamacare, to get much of anything done.

But what was it that Obama used to say? "Elections have consequences," and you've got to play with the cards you're dealt. It's not complicated: You can either do the hard work to build a consensus and pass lasting legislation or you can toss off victories that won't last very long. Now Trump, like Bush and Obama, is mostly opting for the latter. What is it with these baby-boomer presidents anyway? Not a single one could pass the marshmallow test.

Indeed, gridlock didn't stop the president and Congress from pulling together when they wanted to. As Veronique de Rugy and I wrote in 2012:

the ostensibly gridlocked Congress reauthorized the Export-Import Bank program that gives money to foreign companies to buy U.S. goods; extended sharply reduced rates for government-subsidized student loans; re-upped the Essential Air Service program that subsidizes airline service to rural communities; and voted against ending the 1705 loan-guarantee program that gave rise to green-tech boondoggles such as Solyndra and Abound. None of these were party-line votes—all enjoyed hearty support from both Democrats and Republicans. Another instance of budding bipartisanship is the pork-laden farm bill that extends sugar subsidies, maintains crop subsidies and creates a "shallow-loss program" that effectively guarantees incomes for farmers at a time when that sector is doing historically well. The bill passed the Senate with 16 GOP votes. Though the House version of the bill is still being worked out, no one doubts it will not only pass, but largely resemble the Senate version.

My point in bringing up the relative ease with which Trump pulled America out of the Iran deal isn't (simply) to bash Obama. He's out of office, and Trump and the GOP own the state of the nation. It's to underscore the low-grade, slow-moving constitutional infection that has plagued the 21st century like Hep C. If Congress refuses to do its job, which is to write laws and give clear limits to the executive branch, all we have to look forward to is a series of four- or eight-year lurches in this direction and that as the presidency slides from Republican to Democrat and back again. This is no way to run a corner market, much less a country. But it won't stop until the group Mark Twain identified as America's only native criminal class starts to actually do its job.

Final point to the NeverTrumpers: Realize that everything The Donald does simply by pen and phone will be just as easily countermanded as Obama's own "signature achievements." If a president's signature ain't on a piece of actual legislation, it might as well be written in pencil.

UPDATED 12:30 P.M. ET: Reader Ankush Narula (follow him on Twitter) points me to "If the Iran deal had been a Senate-confirmed treaty, would Trump have been forced to stay in? Nope," a Washington Post article by Andrew Rudalevige. The Bowdoin College professor of government cites recent instances where presidents abrogated treaties without consulting the Senate, notes that it's not fully settled exactly how treaties might be broken, and writes:

It's surely possible that a treaty, in place of an executive agreement, would have wider support. Republicans would have had to vote to ratify it, and thus its abrogation might carry higher political costs. As I noted in 2015, "the difference between seeking a treaty and negotiating an executive agreement is, at base, a political question. So is the outcome of either." And as political scientists Glen Krutz and Jeffrey Peake argue in their book "Treaty Politics and the Rise of Executive Agreements,"executive agreements conducted in "truly unilateral fashion" without even tacit congressional cooperation will be "codified but essentially hollow."

Read the whole thing, which supports the idea that building consensus, which the Iran deal definitely lacked (even some Democrats voiced opposition back in 2015), would help keep agreements in force even if they have not been explicitly voted on as treaties.