WASHINGTON, D.C. -- Married registered voters prefer Republican challenger Mitt Romney over Democratic President Barack Obama by 54% to 39%, according to Gallup data collected from June to August. On the other hand, nonmarried voters break strongly for the president over Romney, 56% to 35%. Marriage is a significant predictor of presidential vote choice even after income, age, race, gender, education, religiosity, region, and having minor children are statistically controlled for.

This "marriage gap" -- the consistent propensity of married individuals to choose Republican candidates in a lopsided fashion -- has long been evident in American politics, and prior research has documented the more basic relationship between marriage and party identification. In recent elections, married voters have voted for the Republican presidential candidate by disproportionately wide margins.

Romney's campaign this year appears to be taking advantage of this predilection for married voters to favor the Republican ticket -- for example, by promising to "honor the institution of marriage" in his acceptance speech at the Republican National Convention on Aug. 30. Republicans are far more likely to oppose gay marriage than are Democrats or independents.

Singles and Those in Domestic Partnerships Overwhelmingly Back Obama

Nonmarried Americans strongly prefer President Obama to rival Mitt Romney, 56% to 35%; this group includes those who are single, in a domestic partnership, widowed, divorced, and separated. Support for President Obama varies among these subgroups -- those who are single (61%), are in a domestic partnership (62%), or are separated (58%) are especially supportive of the president, while the divorced (51%) are somewhat less so, with those who are widowed breaking even.

Highly Religious, Whites Among Those More Likely to Be Married

Being married is related to a number of demographic characteristics that themselves are related to voting choices, which at least partially explains the marriage-vote connection. Americans who describe themselves as "highly religious," as well as non-Hispanic white Americans, those with at least one minor child in the house, individuals aged 30 or older, and those earning at least $5,000 per month are significantly more likely to be married than others surveyed in the June-August sample.

Many of these groups with above-average marriage rates also record higher levels of support for Romney, at least in comparison to the overall sample average. For example, voters who are highly religious (57%), non-Hispanic whites (54%), and those aged 65 or older (52%) disproportionately favor the Republican candidate.

Thus, it is clear that to some extent marriage by itself is not a direct predictor of Republican presidential candidate support, but instead, it is associated with other characteristics that more directly influence voting behavior.

Marriage Influence Holds Despite Other Demographics

Demographics alone do not explain the marriage-voting relationship. A special multivariate statistical analysis found that marriage remains an important predictor of support for Romney vs. Obama even after controlling for age, race, income, gender, education, religiosity, region, and whether a voter has minor children. These findings thus demonstrate that being married has some influence on voting patterns that cannot be attributed solely to common demographics and characteristics among married individuals.

As an illustration, Romney possesses an overwhelming advantage among the "highly religious," (57%), while his support is weaker with the "moderately religious" (45%) and the "not religious" (31%). However, Romney performs comparatively better against Obama among those who are married within each of the three religiosity categories. At the same time, Obama does better among the nonmarried within each religiosity category. Even among Americans who are highly religious, those who are not married support Obama over Romney by a six-percentage-point margin. Among the highly religious who are married, Romney beats Obama by an overwhelming 36-point margin.

Likewise, the marriage gap persists when controlling for race, in that Romney performs better with the married than with the nonmarried, among both whites and nonwhites.

Implications

Married Americans constitute an important part of Republican nominee Romney's voter coalition, and his ability to win the votes of a large portion of this group is crucial to his election hopes. Gallup estimates show Romney currently enjoys support among married voters similar to that of other Republican presidential candidates since 2000; in all instances, married voters were more likely to support the Republican candidate. It should be noted that the current analysis is based on June through August data, and therefore does not reflect recent changes including Obama's post-convention bounce. However, there is no reason to believe that changes in the overall level of support for either candidate would affect the marriage gap.

There are a number of potential explanations for marriage's impact on presidential vote choice. One might be that conservatives and Republicans, with their philosophical commitment to social traditions and customs, are especially likely to get married. Setting aside religious considerations and the innate desire to marry that apply to a broad cross-section of people, it may be that Republican voters also consider marriage an expression of civic responsibility that stems from their political beliefs. On that point, a Gallup poll earlier this year found that 45% of married individuals believed their views on social issues to be conservative or very conservative, while 30% of the nonmarried described their social beliefs similarly.

On the other hand, it is entirely possible that marriage and the ensuing transformation of a person's life that accompanies such an action have a profound impact on a person's political philosophy. Such changes include a stronger interest in matters of importance to a household/family, such as a desire for greater security and stability, and that may alter a person's vote preference.

Current trends show that fewer Americans are getting married. According to U.S. Census Bureau figures, 72% of all adults in America in 1960 were married. By 2000, that figure had fallen to 57%. In 2012, 53% -- a slim majority -- of Americans are currently married. This decline in marriage rates may mean future Republican presidential candidates will be forced to broaden their appeal among the nonmarried; otherwise, they may find themselves depending on an ever-shrinking voting bloc.

The 2012 election is often framed in the competing demographics of the two rival bases: old vs. young, racial/ethnic minority vs. whites, and the rich vs. the poor. This analysis offers one more layer to this segmentation -- the married as opposed those who are not. While the candidates have framed this presidential contest as a battle among conflicting ideologies, it increasingly looks to be a matter of differing demographics as well.

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