As America’s Supreme Court heard arguments on Tuesday on the constitutionality of gay marriage, Politico reported that many of the Republican Party’s contenders for the presidential nomination have struck a far less divisive tone on the issue than they did in the past. While they continue to tell social conservatives they oppose marriage equality, “It’s getting harder to believe them,” according to the political news website.

Republicans are struggling with one of 2015’s first cultural litmus tests, not wanting to offend social conservatives, a dominant force, especially in Iowa and South Carolina, or to upset the [Republican Party]’s donor class that’s increasingly pushing candidates to better align their position with the nation’s broader, rapidly changing electorate.

Last year, support for gay marriage reached 55 percent nationwide, according to the polling organization Gallup. That is up from just 40 percent in 2008, the year Barack Obama was elected president.

Even more tellingly, 63 percent of Americans now say gay couples should have the right to adopt children. The last time Gallup asked the question, in 2007, 50 percent of Americans said they shouldn’t.

Support for gay rights is strongest among Americans under the age of thirty. 73 percent of them say gay marriage should be legal while only 42 percent of pensioners agree.

This is a dilemma for both major parties. Democrats and Republicans who turn out to vote in presidential primary elections tend to be older and socially more conservative. This is especially true for Republicans whose primary electorate largely overlaps with the 45 percent of Americans who still oppose marriage equality.

Hence the candidates’ hedging on the issue. When Senator Ted Cruz, a firebrand from Texas, spoke with wealthy donors in New York City last week, he said he would love his daughter “just as much” if she were a gay. A few days later, he asked supporters in the early-voting state Iowa to pray with him that the Supreme Court wouldn’t rule in favor of gay marriage.

Jeb Bush, the former governor or Florida, Scott Walker, the governor of Wisconsin, and Marco Rubio, a junior senator who declared his candidacy earlier this month, have all said they would attend the weddings of gay friends. Yet all three insist they don’t want to change the definition of marriage.

Outright supporting gay rights may be a bridge too far for even socially moderate Republicans like Bush and Rubio — for now. But the party knows it has to change.

A report commissioned by the Republican National Committee after Mitt Romney was defeated by Obama in 2012 recognized that “there is a generational difference within the conservative movement about issues involving the treatment and the rights of gays — and for many younger voters, these issues are a gateway into whether the party is a place they want to be.”

Gay marriage may not be a winning issue for Republicans but it is becoming a losing issue. If they want to remain competitive in national elections, they must appeal to the growing segment of the population that doesn’t care to continue to discriminate against gays.

The Supreme Court might just do those Republicans who agree a favor if it rules for gay marriage in June. If the highest court declares gay marriage legal, there won’t be much point in continuing to fight it.