Blame Monica Lewinsky.

More precisely, for Democrats wondering how their party ended up in the ditch, Bill Clinton’s sexual dalliance with a then-22-year-old intern is an excellent place to start. Because it’s clear in retrospect that the most significant aftermath of l’affaire Lewinsky was not the subsequent impeachment of President Clinton but the death of the New Democrat movement that was until then driving his administration.

Now, there’s always been more than a little mythmaking about Mr. Clinton’s political moderation. Notwithstanding some campaign rhetoric and a stint as chairman of the Democratic Leadership Council when he was governor, there wasn’t much sign of the New Democrat in President Clinton until Newt Gingrich and his fellow Republicans gave him a drubbing in 1994. Before Republicans took the House and reset the national agenda with their “Contract with America,” the “moderate” President Clinton had reneged on his promise of a middle-class tax cut and tried to push through the unpopular HillaryCare bill.

But give the Big Dawg his due. When the Republicans took Congress, he had the wit to recognize he’d been too far in front of the American people. So instead of fighting the GOP agenda he tried to co-opt it, especially on the economy.

The result? With the exception of the North American Free Trade Agreement signed in 1993, the achievements of the Bill Clinton presidency date mostly from after the Republican revolution and include welfare reform and repeal of the Glass-Steagall restrictions separating commercial from investment banking. As Mr. Clinton himself put it in the 1996 State of the Union, “the era of big government is over.”