“Udall is running his entire campaign on social issues,” said Brad Dayspring of the National Republican Senatorial Committee. “All they talk about is birth control, ‘personhood,’ abortion.”

So will many other Democrats this fall. They aim to match President Obama’s feat in 2012, when the incumbent used topics such as same-sex marriage and contraception as weapons to offset his vulnerability on the economy. That they would even try while facing the older, whiter, more conservative midterm electorate shows how thoroughly the politics of social issues have turned upside down…

American households have changed significantly. Nearly half of adults are unmarried. Fully 10 percent of opposite-sex married couples are interracial or interethnic. Acceptance of same-sex marriage has expanded with astonishing speed…

Democrats profit politically — among young voters, college graduates, single women, blacks and Latinos — from the sense that they welcome these cultural shifts while Republicans resist them.