President Obama made a last-minute push to get black voters to the polls in some key states early this week, but it wasn’t nearly enough to preserve the Democratic majority in the Senate.

The president cut radio ads for Sen. Kay Hagan (D-N.C.) and former Florida governor Charlie Crist (D) in two of the tightest races in the country. He also did radio interviews with 14 stations in key states, the White House disclosed late Tuesday.

If there were two states where such an effort could matter, it would have been North Carolina and Georgia, where Obama previously did a radio interview on an African American station in support of Democratic Senate candidate Michelle Nunn.

Exit polls Tuesday night in Georgia suggested that the black share of the vote there (29 percent) was lower than in the 2010 and 2012 elections, while in North Carolina (21 percent) it was slightly up from the last midterm elections four years ago but down from 2012, according to numbers compiled by the Joint Center for Political and Economic Studies.

Hagan and Nunn were winning this vote by similar margins as Obama, each taking more than 9 in 10 black votes.

From the Senate to gubernatorial races, here are the key Republican winners from the 2014 midterm elections. (The Washington Post)

But neither of them was able to overcome the anti-Obama environment and their struggles among white voters. Nunn fell to businessman David Perdue (R), while Hagan was edged out by North Carolina state House speaker Thom Tillis (R).

Hagan put up more of a fight. She trailed Tillis by 24 points among white voters, who voted against Obama by 37 points in 2012 — a significantly bigger margin. This was helping her make up for the smaller share of African American voters.

Polls had long shown Hagan holding a narrow lead in the North Carolina race, which Republicans targeted from the outset of the 2014 election cycle. It was one of seven states carried by Mitt Romney in 2012 that Democrats were defending this year, but it had proved the most challenging of the seven for the GOP.

Nunn, by contrast, was winning only 25 percent of the white vote, barely better than Obama’s 23 percent showing six years ago, the last year for which exit polls are available in Georgia. And given that Obama lost the state by five percentage points in 2008, Nunn needed to do a lot better.

Of course, Nunn did not need to beat Perdue on Tuesday night; all she needed to do was hold him below 50 percent of the vote to force a January runoff. But she was unable to do that, falling by eight points and with Perdue easily clearing 50 percent.

Hagan’s near-miss appeared to be aided, at least in part, by the presence of a Libertarian Party candidate, Sean Haugh. Exit polling showed Haugh was indeed carrying a significant share — 5 percent — of white voters, who favored Tillis. But Haugh was also carrying 8 percent of voters under age 30, which was a strong demographic for Hagan.

Nunn and Hagan were clearly fighting a difficult environment in which about one-third of voters said they were casting their ballots expressly in opposition to Obama — vs. just 1 in 5 who said their votes were in support of the president.

But among voters who said Obama was not a factor, Hagan was leading by 35 points, while Nunn was winning by a margin of 18 points.

Another key state holding a Senate race Tuesday, Iowa, showed a similar dynamic, with Democrat Bruce Braley leading by 25 points among voters who said Obama was not a factor in their vote.

In that state, though, Republican state Sen. Joni Ernst defeated Braley by winning 48 percent of the female vote and beating Braley by 16 points among men.

And while Iowa is far less racially diverse than Georgia and North Carolina, the electorate was again looking more like 2010 — a strong GOP year — than 2012, which was a solid year for Democrats. There were slightly more Republican voters heading to the polls than Democrats. In 2012, the electorate was 33 percent Republican and 33 percent Democratic.

Iowa was seen as particularly pivotal for GOP Senate control heading into Tuesday night. North Carolina, despite its early prominence on the GOP’s target list, was seen as a tougher win.

Georgia, meanwhile, was looking like a potential spoiler for Democrats a couple weeks ago, after Democrats landed a strong attack on Perdue’s history of outsourcing jobs.

Thanks to strong opposition to Obama and Democrats’ struggles with Southern whites, the GOP won all three races Tuesday.