Another election day has come and gone, and we’ve seen another, admittedly surprising, failure for those who believe anti-immigration fervor is the new driving force in American politics. Virginia Republicans were counting on the matter to help them retain control of the State Senate there, but it did not do the trick, and for the first time in a decade, Democrats are in control of the legislature in Richmond.

Some partisans on the issue claim a partial victory because of a Republican win by an anti-immigration guy in Virginia’s Prince William County, but since the victor was reelected, it is a mite questionable how potent the issue was in securing his return to his own seat. What is unquestionable, though, is that in a fascinating repeat of a failed electoral strategy in Virginia’s governor’s race last year, Republicans thought they saw a way to win by thumping hard on immigration — and they lost instead.

You would think, from the bottomless depths of the populist sentiment on the matter dating back to 2004, that anti-immigration fervor would be a potent issue at the ballot box. After all, despite polling that showed majority support for most of the provisions in the immigration-reform bill proposed earlier this year, the measure fell apart owing largely to a potent grass-roots revolt on the Right. (The bill deserved its fate; it was disastrously constructed and internally inconsistent, but the proximate cause of its failure was not in the drafting but in the wild hostility to any manner of immigration reform that was not exclusively punitive.)

And yet, in almost every recent electoral contest in which a candidate has sought to harness the emotional power of the anti-immigration cause to propel him to victory, the issue hasn’t done the trick.

In San Diego two years ago, Minuteman founder Jim Gilchrist tried to get himself elected to the House as a single-issue anti-immigration candidate and failed twice. Vulnerable Arizona Rep. J.D. Hayworth preached fire and brimstone on the issue last November and was turned out anyway. Another Arizonan, Randy Graf, sought victory with immigration as a single issue last year and was slaughtered at the polls. Only California Rep. Brian Bilbray, in a complex special election in 2005, made effective use of anti-immigration fervor to get himself back to Washington.

The common presumption is that immigration has become an issue of central importance in electoral politics. At some point, pretty soon, there’s going to have to be hard evidence of that or Republican politicians will begin to face the very real possibility that their party is turning Hispanics into an implacably hostile anti-GOP bloc without securing any real political gain for it.