Sen. Elizabeth Warren (D-Mass.) has said repeatedly that she won't run for president in 2016, and yet the idea persists: That Hillary Clinton could find herself vulnerable to a more liberal primary opponent.

The problem? Almost all of the most recent data suggests that Clinton doesn't have any real problems on her left flank. Indeed, she's actually stronger with liberals than  she is with more moderate Democrats. And very, very few liberals have anything but nice things to say about her.

To wit:

* A new CNN/Opinion Research poll shows that when voters are asked whether they would prefer Clinton, a more liberal alternative or a more conservative one, about twice as many non-Clinton voters say they prefer the more conservative one (20 percent) to the more liberal one (11 percent).

* A Washington Post/ABC News poll this month showed Clinton taking a bigger share of the vote in the 2016 primary among self-described liberals (72 percent) than among moderate and conservative Democrats (60 percent).

* The same poll shows 18 percent of moderate Democrats don't want Clinton to run. Just 6 percent of liberal Democrats agree.

* The WaPo-ABC poll also shows liberal Democrats approve of Clinton's tenure at the State Department by a margin of 96-1, while moderate Democrats approve of it 84-12. Sixty-seven percent of liberals strongly approve of Clinton's performance, nearly 9 in 10 say she is a strong leader, and only slightly fewer say she's honest and trustworthy.

* A Fox News poll conducted in April showed just 5 percent of Democrats and 6 percent of liberals said they thought Clinton was "too conservative" for their taste. By contrast, 23 percent of Republicans and 35 percent of tea party supporters said New Jersey Gov. Chris Christie (R) was "too liberal" for them.

As this last poll demonstrates, the ideological parsing is just much, much stronger on the Republican side these days. And while the idea of Clinton getting a liberal primary challenger like Warren is tempting theater for political analysts like The Fix, we all seem to be projecting the internal GOP squabbles on to the Democratic Party, and it just doesn't quite fit. The numbers right now just don't show anything close to a gaping hole on Clinton's left flank.

As we've argued before, there is indeed plenty of desire among Democrats for the message being touted by folks like Warren, and she would likely quickly gain support if she changed her mind and decided to run.

But the same crowd that likes Warren's message and would seem to like Warren herself seems more than content with the idea of Hillary Clinton for president -- at least right now. Things can always change, and the Clintons can indeed to tied to the "1 percent" pretty easily. But there's plenty of work to do in prosecuting that case.

Should anyone attempt to go at Clinton from the left, they really shouldn't expect to catch fire immediately.