Despite their vast electoral success on November 2, many Republicans are finding it hard to swallow the tough Senate race losses to Harry Reid in Nevada and Michael Buck in Colorado. They are also perplexed by the surprisingly close win in Pennsylvania and the very wide margin of victory for Dems in the California Senate and gubernatorial races.

It isn’t precisely known why these races went the Democrats’ way or, perhaps as frustratingly, why the polls over-predicted for Republicans in most of them. In the months to come, there will be no shortage of explanations for these developments. One particular explanation, though, should be dismissed: The theory that in close races like the one for U.S. Senate in Nevada, it was Hispanic voter umbrage from Republicans’ purportedly “anti-immigrant” stance that made the difference. Newsweek, using data from a liberal Hispanic advocacy group, ran an article suggesting that polls underestimated rates of Hispanic turnout and that Hispanics were responsible for unexpected Democratic victories in Nevada, and possibly even California, Colorado, and elsewhere.

It is not yet known whether or not Hispanics were under-polled. But most of the available data suggests that with the exception of California (where both Republican U.S. Senate candidate Carly Fiorina and gubernatorial candidate Meg Whitman fled from the immigration issue), Republican candidates did relatively well among Hispanic voters. According to the national exit poll, 38% of Hispanics voted for Republicans in House races this year, compared with only 30% in the last midterm elections in 2006, a year in which high-profile Republicans like John McCain and Lindsey Graham were leading efforts for “comprehensive immigration reform” (i.e., amnesty). The national Hispanic vote for Democrats dropped 9 percentage points, from 69% in 2006 to 60% in 2010, only 1 percentage point behind the 10-point drop in the share of white votes for Democrats, which went from 47% to 37%. By way of comparison, black voters remained at 89% for Democrats in both elections.

There is other evidence refuting the notion that Hispanic voters are motivated primarily by the immigration issue and turnout in large numbers to defeat anti-illegal immigrant candidates. In Florida, Governor-Elect Rick Scott won 50% of the Hispanic vote despite having come out in favor of Arizona’s tough anti-illegal immigrant enforcement law and being attacked for doing so by his Democratic opponent, Alex Sink. A survey conducted last February by the pro-restriction but highly regarded Center for Immigration Studies found that 56% of Hispanics think that immigration to the U.S. is too high, that 61% felt illegal immigration was mostly about poor law enforcement, and that 52% support enforcement to encourage illegals to go home. Only 34% support conditional legalization, or “amnesty.” According to a Pew Hispanic Center Study in 2007, 45 percent of Hispanics oppose giving driver’s licenses to illegal immigrants.

This data does not exactly support Newsweek’s contention that Sharron Angle’s “harsh” anti-illegal immigrant attack ads on incumbent Senator Harry Reid “infuriated Hispanics in Nevada and beyond.”

Indeed, Hispanic voters don’t even seem to have been particularly “furious” at Angle in Nevada. Hispanics made up 12% of the voters in Nevada in the 2006 midterm election and 24.4% of the state’s population, according to the CNN exit poll and the U.S. Census. In 2010, Nevada Hispanics made up 15% of the electorate and 26.5% of the population, meaning that more than two-thirds of the increase in the percentage of the electorate made up of Hispanic voters in Nevada between 2006 and 2010 is a function of population increase, not turnout rate jumps spurred by fear of Republican know-nothingism.

Besides, Angle’s 30% of the Hispanic vote was a higher percentage than John McCain’s share of the Hispanic vote in Nevada during the presidential race of 2008 (22%). McCain was well-known among Hispanics for his effort to push through comprehensive immigration reform, and he proudly refused to make Obama’s support for giving driver’s licenses to illegals a campaign issue. Partly as a result, whites in Nevada dropped as a percentage of voters to 69% from 77% just two years earlier, and they gave McCain the same 53% of their vote as they gave to Angle. Both McCain and Angle lost Nevada by roughly the same 5-to-7-point margin.

In fact, if any lesson is to be learned from Angle’s defeat, it should be that Republicans have to perform strongly among white voters to win in battleground states, but also that Republican candidates need more than an anti-illegal immigration platform to appeal widely to whites. Angle, “a chronically gaffe-prone candidate, who is running as a proud Christian conservative in Sin City,” received a much lower percentage of the white vote than Nevada Republican Senator John Ensign received in the midterm election of 2006, which Ensign won handily with a 13% margin. Ensign received 60% of the white vote compared with Angle’s 53%. Ensign also received 45% of the Hispanic vote, as opposed to Angle’s 30%. But the white vote was more numerically important. Taking these voting percentages, along with the voting-age population and voter participation rates prepared by George Mason University’s United States Election Project, if Angle had managed to keep Ensign’s 60% of the white vote, she would have received 47,654 more votes than she did – possibly enough to put her over the top. On the other hand, if Angle had managed to keep Ensign’s 45% of the Hispanic vote, she would have received only 34,216 additional votes.

The point is also illustrated by the powerful contrast between the campaigns of Sharron Angle and Arizona Governor Jan Brewer, who ran for reelection as the anti-illegal immigrant candidate in a state demographically similar to Nevada. Brewer won her election by a 10-point margin, despite receiving only 28% of the Hispanic vote. The difference between Angle and Brewer was the white vote, 60% of which went to Brewer.

There are other, more convincing reasons why Sharron Angle lost to Harry Reid in Nevada, why Ken Buck lost to Michael Bennet in Colorado, and why two excellent Republican candidates in California lost statewide elections by resounding margins. They have mostly to do with the more effective Democrat “ground game.” Byron York reports in the Washington Examiner that “[n]ationally, the American Federation of State, County and Municipal Employees spent $91 million trying to elect Democrats. A good chunk of that went to Reid, mostly for get-out-the-vote operations.”

Whatever the case, two things are clear in the wake of the 2010 mid-terms:

1) If immigration law enforcement and border control are promoted with humanity, decency, and – perhaps most important – with conviction, Hispanics (and whites, for that matter) won’t spurn candidates who support them, and

2) the white middle class is by far the Republicans’ most important constituency.

Republicans won whites in 2010 by a 23-percentage point margin (60 to 37 percent) and had their best showing ever. In 2006, Republicans won whites by a mere 4 percentage points and suffered electoral setbacks that led to their monumental defeat in 2008. Appealing to the preferences of white voters was clearly the difference.

Seth Forman teaches government and politics at Stony Brook University and blogs at www.mrformansplanet.com.