When it comes to the border, we're all Neanderthals now.

When the amateur border guards, the Minutemen, first set up with their lawn chairs and binoculars at the U.S.-Mexico border and started talking about the need to build a fence, polite opinion scoffed. Now, the fence almost represents a consensus position, embraced by the left and right alike, from likely Democratic presidential nominee Hillary Clinton to the rabble-rousing pro-enforcement conservative Rep. Tom Tancredo of Colorado.

Sixty-four Democrats just voted with Republicans in the House to pass legislation authorizing 700 miles of double-layered fence along the border. The Senate recently voted 94-3 to spend nearly $2 billion on 370 miles' worth of fencing and will take up the House bill soon. As the panicked National Immigration Law Center says, "In recent days, there has been a serious deterioration of the position of pro-immigrant forces in Congress."

This political state of play is the exact reverse of what was widely predicted earlier in the year when illegal immigrants were marching in the streets; Hispanic and church groups were decrying the harsh treatment of illegals in a pro-enforcement House bill; and the Senate was passing an amnesty bill euphemistically dubbed "comprehensive reform." Back then, it was assumed that the crazies in the House would bend to a Senate bill endorsed by all the great and the good. But a funny thing happened on the way to "comprehensive reform" — the political marketplace worked.

Instead of embracing the Senate approach, the House undertook field hearings around the country. The delay gave candidates a chance to sample public opinion that is markedly sympathetic to the crazies. Consider the Democratic senator from Nebraska, Ben Nelson, who is running for re-election. He once opposed crackdowns on illegals in his state, but now complains that illegal labor crowds out American workers. He voted for the funding of the fence the other day, and his Republican opponent is also singing a tougher song on immigration.

The same dynamic applies in most other close Senate races. The public has long supported better immigration enforcement, but Washington has disdained and ignored it. Washington partakes of elite attitudes on immigration (Tancredo used to get sneered at even by fellow Republicans when he talked about a fence), and its strongest lobbies on both the right and left love a robust inflow of cheap, illegal labor. The high-profile debate on immigration, however, coupled with an election, has forced the Beltway to give public opinion its due.

This is not to say that increased enforcement has no enemies. Most House Democrats representing safe, liberal districts still oppose it, and Senate Minority Leader Harry Reid might yet find a way to derail the fencing provision in the Senate. The argument against the fence is, as Arizona Gov. Janet Napolitano has put it, "You show me a 50-foot wall, and I'll show you a 51-foot ladder at the border." This is true, and also beside the point. If illegals have to deploy 51-foot ladders to get here, their transit manifestly is going to be more difficult, and therefore fewer will attempt it.

But a fence itself isn't sufficient. The key is stepped-up interior enforcement to cut off the jobs magnet that draws so many illegals here. The so-called Basic Pilot program — a small, voluntary system allowing employers to verify the legal status of their employees by computer — must be expanded and made mandatory. The Social Security Administration also has to tighten up its system of notifying employers when they hire people using fake Social Security numbers. It currently is full of holes that exist as a matter of policy to allow businesses, with a nod and a wink, to keep hiring illegals. These measures would really bite, and therefore are sure to encounter the bitter opposition of pro-illegal groups.

In the meantime, score one for the Neanderthals. They have shown that Washington can be made to respond to public opinion on immigration, for a change.