Voters fill in their ballots as they vote in the U.S. midterm elections at a polling place in Colorado on Tuesday. Reuters

Millennials did vote Democrat in the 2014 midterm elections, after all. Early exit poll data showed that in House of Representatives races, 55 percent of people ages 18 to 29 voted for Democratic candidates. Young voters also tended to choose Democratic candidates in Senate races. But getting the youth vote wasn't enough to swing many of Tuesday's key races. As voters' ages climbed, Republican support grew, according to the Center for Information and Research on Civic Learning and Engagement.

Young people voted Democratic by a 13-point margin, ABC News reported, down from 2012's 22-point margin. In 2010, they chose Democratic House candidates by a 17-point margin and Democratic Senate candidates by a 15-point margin, according to the research center. Millennials comprised 13 percent of voters, 1 percentage point higher than in 2010, when youth voters made up 12 percent of the electorate.

In North Carolina, 54 percent of millennials chose Democratic nominee Sen. Kay Hagan -- who won 71 percent of the youth vote in 2008 -- but she lost to Republican state House Speaker Thom Tillis. In Georgia, 59 percent of the youth voted for Democratic candidate Michelle Nunn. But she ultimately lost to Republican candidate David Perdue, who received 39 percent of the youth vote.

In Iowa, Democrat Rep. Bruce Braley received 54 percent of millennials' votes, but lost overall to Republican Sen. Joni Ernst. In Kansas, where Democrat Chad Taylor dropped out of the Senate race in September, 60 percent of millennials voted for Independent candidate Greg Orman. He still lost to Republican Sen. Pat Roberts overall.

Half of millennials voted liberal in Louisiana, but only 36 percent voted Republican. No candidate was able to secure 50 percent of the vote overall, triggering a runoff election planned for December. Fifty-eight percent of millennials voted for Democrat Sen. Jeanne Shaheen in New Hampshire, and she won.

The youth's share of the electorate has hovered around 12 percent for the past 10 years of midterms, so this year's 13 percent was a small increase. But, the research center cautioned, a rise in youth share doesn't necessarily mean a rise in turnout. Those numbers were due to be released later Wednesday.