Former U.S. secretary of state Hillary Rodham Clinton takes part in a roundtable of young Nevadans discussing immigration as she campaigns for the 2016 Democratic presidential nomination at Rancho High School in Las Vegas on May 5, 2015. REUTERS/Mike Blake

On Tuesday, my Post colleagues Dan Balz and Peyton Craighill discussed the results of a new Washington Post-ABC News poll, which found that Hillary Clinton’s favorability ratings were lower than in any Post poll since 2008.  The University of Wisconsin’s Charles Franklin put together this helpful graph, which shows that other polls are registering this same trend.

franklin_hrc

Here was my question: who is driving this decline?  Is it Republicans, in which case Clinton is losing support among voters who mostly won’t vote for her anyway?  Or is she losing support among independents, or even Democrats?

Craighill provided me some additional numbers.  He broke down the trend among three groups: (1) Democrats and independents who lean Democratic, (2) “pure” independents who don’t lean toward any party, and (3) Republicans and independents who lean Republicans.  This helps isolate those independents who are truly independent and not, as much research has found, closet partisans.

Clinton’s standing among Republicans hasn’t changed in the past two months.  Only 14 percent had a favorable view of her in this poll (vs. 82 percent who had an unfavorable view). The split in March was nearly identical: 15 percent-82 percent.

But Clinton has lost support among independents. In March, 45 percent had a favorable view and 44 percent had an unfavorable view, for a net approval rating of +1 point.  That has now fallen to -14 points (37 percent-51 percent).  Craighill notes that the sample size of pure independents is small (86 in the March survey and 97 in the May survey).  So take this trend with a grain of salt.

Even more striking is that Clinton has lost support among Democrats. In March, her net favorability rating was +59 points (78  percent-19 percent). It is now +50 percent (72 percent-22 percent).  Of course, she is still very popular among Democrats. But because Democrats are far more numerous than pure independents, they are driving most of the trend that the Post polls document.

On the one hand, this is bad news for Clinton.  Pure independents are less likely to vote than partisans, but at least some will. No candidate wants a net favorability rating of -14 points among this group.

And the fact that Clinton has lost ground among Democrats suggests that the negative news coverage of the past two months — e.g., regarding her e-mails while secretary of state — actually took some toll.  If it were just making Republicans like her less, that would be one thing. This is different.

But there is good news for Clinton too.  Clinton’s standing among Democrats will likely only improve as the campaign goes on — particularly when there she has a clear Republican opponent.  As I’ve noted before, campaigns almost always rally each party’s voters behind their nominee. So Clinton’s decline among Democrats is probably temporary.

Moreover, as Franklin also observed, Clinton is viewed more favorably than almost every GOP candidates — and none of the Republicans are viewed that favorably, period.  The interesting question ahead is how views of these Republicans change, or don’t change, as more and more Americans become familiar with them.