In this familiar sequence, the role of one man deserves study, as emblematic of the age as a whole. That person is of course Mitch McConnell, 75-year-old senator from Kentucky, leader of Republicans in the Senate for the past decade.

I'm deeply saddened by the horrific violence in Florida. Praying for the victims, their families, and the Parkland community. Always grateful for first responders who charge into harm’s way. — Leader McConnell (@SenateMajLdr) February 15, 2018

A history of our era will show Mitch McConnell as both the most effective purely partisan figure of the time—LBJ in the Senate, Sam Rayburn in the House, their records will pale—and a person uniquely destructive of trans-partisan governing norms. How has he changed norms? For the full picture I refer you to a wonderful short 2014 book about McConnell by Alec MacGillis, called The Cynic (well reviewed in The New York Review of Books by Robert Kaiser), and a prescient 2011 profile in The Atlantic by Joshua Green, called “Strict Obstructionist.”

Of course since those accounts, McConnell changed national and political history with his unprecedented refusal to consider Barack Obama’s nominee for the Supreme Court, Merrick Garland, and by blocking the Obama administration’s efforts to issue a bipartisan warning about Russian election interference during the summer of 2016. Both moves enhanced the chances of Donald Trump’s election: the Garland stonewall in giving conservatives a clear-cut reason to vote for a man whose policies and personality might otherwise leave them queasy, and the Russian-interference stonewall in making that issue seem a fringe concern. Although no one suggests that this is the reason for McConnell’s actions, it’s a matter of historical record that his wife, Elaine Chao, who had been secretary of labor for George W. Bush, was named to another cabinet position, as secretary of transportation, by the victorious Donald Trump.

McConnell’s effect on gun legislation is representative of the politics of this issue and of McConnell’s instincts and influence overall. The crucial moment came after Obama’s reelection victory over Mitt Romney, in 2012.

Five weeks after the election, on December 14, a disturbed 20-year-old with an AR-15 went to the Sandy Hook Elementary School in Newtown, Connecticut, and shot dead 20 little six- and seven-year-old children, plus six staff members.

At the time, it seemed unimaginable. At the time, it seemed that this atrocity might be the one that finally changed the public mind and thus public policy about dealing with guns. At the time, it seemed that pictures of these children and their families might have an effect like that of horrific images from the Vietnam era, for instance 9-year-old Kim Phuc running in terror, naked, after a napalm attack.

Associates of Barack Obama say that he considered the day he got the Sandy Hook news the worst day of his presidency. And two months later, in the first State of the Union address of his second term, he made the case for gun legislation with a passion and intensity quite rare in these big, formal speeches.