The young apparently haven't seen enough hope and change since 2008.

Voters under 30, who overwhelmingly voted for President Obama two years ago, not only showed up in much lower numbers Tuesday but were also less willing than in the last election to strongly support Democrats.

Exit polls showed voters ages 18 to 29 made up 11 percent of the electorate, a sharp drop from the 18 percent in 2008 and the lowest percentage in two decades. And those voters, who backed Obama by 34 points in 2008, backed congressional Democrats in 2010 by only 16 points.

(The percentage of the electorate is used as a measure because turnout is always smaller in congressional elections than in presidential elections, for all groups.)

The drop-off was even more substantial in some key states. In California, one of every five voters in 2008 was between the ages of 18 and 29, compared with about one in 10 on Tuesday.

Voters younger than 30 still gave Democrats a boost. Every other age group favored the GOP, including a whopping 18-point advantage for Republicans among voters older than 65.

But the numbers suggest that Obama's aggressive appeals to young people in the last month before the election, as well as the rally of comedians Jon Stewart and Stephen Colbert in Washington over the weekend, did little to inspire young voters.

"Turnout for young people is always lower in a midterm election," said Michael McDonald, a government professor at George Mason University who studies data on voting and turnout.

But, he added, "there was some Democratic disillusionment in this election."

There was a slight drop in support from another strongly pro-Obama group: black voters, who made up 13 percent of the electorate in 2008 compared with 10 percent in 2010.

But the plunge among youths added more to the party's woes.

Heather Smith, president of Rock the Vote, a group that tries to register young people across the country, blamed a lack of inspiration from candidates and the airing of negative ads for turning off young voters.

"The political campaigns and their leadership failed to do their job," Smith said. "Unfortunately, the president was not on the ballot."

Staff polling director Jon Cohen contributed to this report.