WASHINGTON — As the electorate evolves with each election cycle because of changing demographics, there is one constant: white evangelicals. Once again, they made up one-quarter of the electorate and voted heavily for the Republican presidential nominee.

White voters, as a share of the electorate, have been on a steady descent from 88 percent in 1980 to 70 percent in the most recent election, according to exit polling. Yet the share of white evangelical voters has remained remarkably static.

After ticking up from 23 percent of the electorate in 2004 to 24 percent in 2006 and 26 percent in 2008, the share of the white evangelical vote has been unshaken at 25 percent in 2010, 26 percent in 2012, 26 percent in 2014, and 26 percent in 2016. Over that same time period, the share of white voters has dipped 7 points, apparently because of a decrease in white non-evangelicals.

Once again, white evangelicals overwhelming supported the Republican candidate for president, this time going 81 percent to 16 percent for Donald Trump. That’s the largest margin in recent memory.

White evangelicals supported GOP congressional candidates 78 percent to 20 percent in 2014, Mitt Romney 78 percent to 21 percent in 2012, Republican candidates 77 percent to 19 percent in 2010, Arizona Sen. John McCain 74 percent to 24 percent in 2008, and President George W. Bush with 68 percent and 78 percent in 2000 and 2004 respectively.

The 2006 elections appear to be the outlier, when Democratic congressional candidates lost white evangelical voters by just 17 points. The 2002 exit polls were never released because of fundamental sampling problems.

Even though she lost white evangelical voters overwhelming, Hillary Clinton still won the popular vote, so it might be easy for Democrats to ignore this deficit. But Michael Wear, President Barack Obama’s religious outreach director for the 2012 campaign, recently made the case that if Clinton had simply matched Obama’s percentage of the white evangelical vote in Michigan and Florida, it would have overcome her losses in those states.

Her lack of support among evangelicals wasn’t surprising.

“The Clinton campaign ran a campaign that employed religious references — primarily as a way to accentuate a critique of her opponent’s moral character — but it included little religious outreach from the candidate herself,” Wear wrote recently in The Washington Post. “Hillary never directly asked for the support of evangelicals. She never had an interview with a major evangelical publication or outlet. Her campaign decided, as Democrats have often desired to, that religious voters — with limited exceptions — did not need to be sought in order to win.”

“For evangelicals who feel embattled, isolated and marginalized by the onslaught of cultural change from sexual liberation to same-sex marriage to the coarsening of culture, Trump promised that he would relieve the pressure,” Wear wrote.

Clinton’s lack of a strategy to evangelicals was even more fatal, considering her showing with secular voters. She also struggled with the faithless.