House Democrats and Republicans have never looked so different, and the GOP could become whiter and more male-dominated this year.

The folks at FiveThirtyEight took a look this week at the number of minorities and women in elected office and found a widening “diversity gap” in the U.S. House of Representatives, projecting that after the 2014 midterm elections, the diversity gap between Democrats and Republicans in the House will be the largest it’s ever been.

Though both major parties were composed almost entirely of white men as recently as the 1950s, the Democratic Party has changed to reflect the makeup of the United States, while the GOP has remained overwhelmingly white and male. As David Wasserman of FiveThirtyEight noted:

On Election Night in 2012, when it was clear Republicans would comfortably hold onto the House despite winning 1.4 million fewer votes than Democrats in House races, Democrats took pride in a different statistic: For the first time ever, women and minorities would compose a majority — 53 percent — of their caucus. Meanwhile, the share of women and minorities in the GOP House conference went down, from 14 percent to 11 percent.

[….]

In 1950, 98 percent of House Democrats and 97 percent of House Republicans were white men. In the 64 years since, that share has fallen 51 points for Democrats, but only 8 points for Republicans. Today, all but one of 20 GOP committee chairs in the House are white men (Rep. Candice Miller, who chairs the House Committee on Administration, is the exception).

FiveThirtyEight’s House demographic breakdown includes a few explanations as to why Democrats have more successfully elected women and people of color to public office: redistricting, strong networks of recruitment (organizations like EMILY’s List), and party values that emphasize diversity.

Another explanation may be that, as demonstrated in the 2012 election of President Obama, Black Americans tend to vote for Black candidates, Latinos vote for Latino candidates, whites prefer white candidates, and so on—leaving the party with few candidates of color and low minority population turnout much less likely to elect people who aren’t white men.

Political observers have not been surprised that the Republican Party is full of white men—the party has in the past few years been criticized for holding all-male fundraisers, bill signings and debates, and committee hearings, many of which discuss issues of particular interest to women, like reproductive rights and abortion access.

And the GOP itself acknowledges that it has an image problem: A survey commissioned by conservative groups this summer confirmed that about 50 percent of women view Republicans unfavorably, describing the party as “intolerant,” “lacking in compassion,” and “stuck in the past.”

GOP leaders have pledged time and again to rebrand by reaching out to women and minorities.

FiveThirtyEight’s deep dive into House demographics points out that today’s GOP representatives look almost identical to Republicans of 60 years ago. In 1950, 97 percent of House Republicans were white men. Today, that number stands at 89 percent.