As the U.S. grows more liberal on social issues, support for gay marriage has reached a record high while the percentage of Americans calling themselves "pro-choice" has just hit a record low.

That's what two new polls reveal. A Washington Post/ABC News poll conducted May 17-20 shows 53 percent of Americans supporting legal gay marriage and only 39 percent opposed.  Only 36 percent supported gay marriage six years ago. In the wake of President Barack Obama's recent announcement that he supports gay marriage, 55 percent of Americans say the issue will not be a factor in their vote in November.

While support for gay rights appears to have obtained unstoppable momentum, support for abortion rights is more complicated. According to a Gallup Poll conducted May 3-6, fewer Americans -- 41 percent -- call themselves "pro-choice" than at any time since Gallup began polling on the issue in 1995. Gallup says the decline is apparent among Republicans, Democrats and Independents.

Americans continue to support legal abortion in large numbers; 52 percent say it should be legal in some circumstances and another 25 percent say it should be legal in all circumstances. But the "pro-choice" label has lost its luster. In 1995, 56 percent described themselves that way -- signaling a 15-point drop in the most recent poll.

(Francis Wilkinson is a member of the Bloomberg View editorial board. Follow him on Twitter.)