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If Democrats were going to hold off a Republican tsunami, they needed their base voters to come out to the polls and pull the lever for the president’s party.

That didn’t happen where Democrats needed it to. Especially with young voters.

Nationally, Democratic base groups – young voters, single women, African-Americans and Latinos -- posted numbers that looked more like the Democrats’ 2010 midterm “shellacking” than Obama’s 2012 re-election victory.

*** Young voters

Most strikingly, voters 18-29 nationwide were only 13 percent of the electorate in 2014 (compared to nearly a quarter for GOP-leaning seniors.) In the 2010 midterms, when Democrats lost a combined 69 House and Senate seats, young voters made up 12 percent of the voting public. In contrast, during Obama’s re-election victory in 2012, nearly one in five voters was under 30.

In some key Senate races, young voters participated at an even lower rate.

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Those voters 18-29 showed up even below that national number in North Carolina (12 percent of the electorate), Georgia (10 percent), Arkansas (12 percent) and Louisiana (12 percent).

*** Single women

More than one-in-five voters this cycle – 21 percent of the electorate -- was an unmarried woman, and a majority -- 60 to 38 percent – voted for Democrats.

Single women made up 23 percent of the electorate during Obama’s 2012 coalition, and they broke significantly harder for Obama in 2012 than for Senate and House Democrats in 2010. Then, 67 percent supported Obama, versus 31 percent for Romney.

*** African Americans

This cycle, black voters made up 12 percent of the national electorate. That’s compared to 11 percent in 2010 and 13 percent in 2012. Democrats particularly needed high black turnout in Southern states like Georgia and North Carolina.

Because exit poll data isn’t available for many of those states – which weren’t contested in the 2008 and 2012 presidential election – it’s not possible to make an apples-to-apples comparison to past presidential contests.

But here’s one data point we do have: In North Carolina, where Democrat Kay Hagan lost her seat to Republican Thom Tillis, black voters made up 21 percent of the electorate. In 2012, that figure was 23 percent.

*** Latinos

After the disappointing collapse of immigration legislation over the last 18 months, Latino turnout didn’t look as rosy for Democrats as it had in past cycles. Latinos made up eight percent of voters in 2014, compared to 10 percent in 2012. In the presidential year, Latinos chose Obama over Romney by a whopping 44 percentage points. This cycle, they picked Democrats by a margin of 28 percent.

In Florida, where Gov. Rick Scott eked out a surprise re-election win, Latinos only made up 13 percent of the electorate, compared to 17 percent in the presidential election in 2012.

Exit poll data isn’t available for another contested state with a high percentage of Latinos: Colorado, an all-mail ballot state.

- Carrie Dann