Sen. Lamar Alexander (R-Tenn.) last week at the Capitol. Alexander says he finds it surprising that so many members of Congress are unfamiliar with the basic rules of legislating. (Aaron P. Bernstein/Getty Images)

The three-day shutdown of the federal government may have had minimal impact on the public, but it served as the latest example of the modern governance-by-deadline dysfunction that has gripped Capitol Hill most of this decade.

Long before Donald Trump took the oath of office, Congress had settled into this exasperating routine of only concentrating on the immediate deadline ahead, casting all other issues aside. The ability to walk and chew gum at the same time — to do any two basic legislative tasks simultaneously — disappeared amid a generational shift that has left the vast majority of lawmakers unaware of how it's supposed to work.

The only recent effort at taming the national debt came in 2011 when the new House Republican majority took the looming federal debt limit hostage to try to force President Barack Obama to cut entitlements. Two years later, a group of conservatives took hold of the annual funding bill for the entire federal government in a bid to force Obama into impaling the Affordable Care Act.

Now in the minority, Democrats have turned the tables over the past two months and done very much the same thing, forcing a brief shutdown in their pursuit of permanent protection for hundreds of thousands of young immigrants brought into the country illegally as children.

The immigrants' fate has been a major issue for at least a decade, compounded by conservative outrage at Obama's 2012 decision to give temporary status to "dreamers" under the Deferred Action for Childhood Arrivals order. Then, in September, President Trump gave Congress an imperative: He was ending DACA, but six months later, in March, so Congress had plenty of time to create a legislative fix to avoid mass deportations.

What has Congress done since then? Basically nothing.

Lawmakers created ad hoc groups, usually overseen by congressional leadership, and held closed-door meetings, and a few committees held hearings.

But not once in the past five months has the House or Senate put legislation on the floor and begun debating the issue to truly test where everyone stands.

In meetings over the past few days, veteran senators made the point to their junior colleagues that the way out of the shutdown was to get Senate Majority Leader Mitch McConnell (R-Ky.) to guarantee that a full, fair debate would begin next month in time for the Senate to possibly map out a bipartisan bill that could become law.

Some senators did not get it.

"It's really surprising. I found in several of these bipartisan meetings, where you might have had 20 or 25 senators, there was a real lack of knowledge about the rules," Sen. Lamar Alexander (R-Tenn.) said. Alexander, 77, said some Democrats were demanding that McConnell put their version of legislation on the floor and try to guarantee an outcome.

That's not how it works, he explained, pointing out how Minority Leader Charles E. Schumer (D-N.Y.) would not want to be bound by that precedent. "Senator Schumer is not going to like that if he becomes the majority leader next year, which he could," Alexander said.

Alexander is known for his bipartisan work on the Health, Education, Labor and Pensions Committee with Sen. Patty Murray (D-Wash.).

She was flummoxed Monday trying to recall the last time the Senate just considered a big piece of legislation that did not have a ticking time-bomb attached to it. Finally, she suggested it was the sweeping K-12 education bill that she and Alexander passed.

That was 2½ years ago, in July 2015. Murray remains skeptical of the Senate's ability to tackle a big issue such as Trump's border security demands in exchange for DACA legislation. "I guess we'll all find out," she said.

In the past 13 months, the Senate has held only three amendment votes on legislation considered under normal rules, according to Democrats. The amendments came on the same bill, about Russian sanctions, which was unanimously approved.

Sen. Lindsey O. Graham (R-S.C.), one of the ringleaders of the bipartisan group that negotiated the end of the shutdown, is not sure the Senate can come together on legislation to protect dreamers — even though nearly 9 in 10 voters want them to stay in the United States.

"Can we take a 90 percent issue like DACA, find a solution and fund the military that's beloved by all of those in the country? The answer should be yes," Graham said. "And if the answer is no, God help us all."

Since Trump was sworn in, the only big pieces of legislation that have had House and Senate floor debate, without some looming deadline, were the bids to repeal the ACA and to overhaul the tax code. But those were considered under fast-track rules that allowed Republicans to steamroll Democratic opposition.

The last real immigration debate came five years ago, when the Senate passed a sweeping bill that would have created a path to citizenship for millions of undocumented immigrants living here illegally if they met a large set of criteria. The House never acted on the bill, and for the remainder of 2013 and 2014 Republicans and Democrats largely gave up on any important legislation unless it had an immediate deadline that, if breached, would lead to a host of bad outcomes.

Members of the bipartisan Senate group say that over several days of long meetings they came to trust one another, not their respective party leaders, and that if they stick together over the next few weeks, they can succeed. And if they do succeed, getting a large bipartisan vote, the pressure on House Republicans and Trump will be immense.

"We feel good that we can put together a bill that will have significant support, and that combined with the popular support for dreamers — which my House colleagues definitely know about — we think will be good," said Sen. Tim Kaine (D-Va.).

Of course, there's a reason they feel optimistic: There's another looming deadline out there. If there's no success by early March, DACA ends.

"There is a forcing mechanism, and it's March 5th," said Sen. Jeff Flake (R-Ariz.), suggesting the images would be politically brutal. "Kids being deported, losing status, losing employment, schooling. That's nothing, I think, we want to face."

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