With his disappointing second-place finish in the Iowa caucuses last night, Mitt Romney joins a growing list of politicians who have failed to ride the immigration issue to success when it counts.

To woo conservative voters, Romney has run a series of hard-hitting ads attacking his Republican rivals for being soft on illegal immigration. His ads and campaign speeches have thumped John McCain for supporting “amnesty” for unauthorized immigrants already here and Mike Huckabee for supporting in-state tuition for the minor children of illegal immigrants.

Although Romney had struck a more constructive tone toward the issue when he was governor of Massachusetts, polls and talk radio have convinced him that sounding harsher-than-thou on illegal immigration would be a key to winning the hearts of conservative Republicans. The strategy didn’t appear to help him in Iowa even though he outspent his rivals by millions of dollars.

Romney isn’t the first politician to push the immigration button and come away empty-handed. Just before the Iowa caucuses, Colorado Congressman Tom Tancredo announced he was dropping out of the Republican primary race even though he trumpeted the most hard-core anti-illegal-immigration stance of any candidate. California Congressman Duncan Hunter barely registered among Iowa caucus goers last night even though he too had staked out a hard-line position against any legalization. And let’s not forget that in 2000, the articulate and amiable Pat Buchanan spent $12 million in taxpayer dollars to spread his anti-immigration message as the Reform Party candidate for president, and attracted a paltry one half of one percent of the vote on Election Day.

Americans have always been ambivalent about immigration, and a solid majority today wants the government to seriously address the problem of illegal immigration. But as I have argued here and here, voters have not rewarded politicians who demagogue the issue. Let’s hope the rest of the Republican field takes notice.