The head of the campaign arm for House Democrats privately advised Dem lawmakers today that they should boycott the House GOP select committee on Benghazi, arguing that participating would legitimize a proceeding that voters already know is a partisan witch-hunt, sources who were present tell me.

DCCC chair Steve Israel made his recommendations to House Democrats at a caucus meeting this morning, making him one of the most prominent Dems to make this case so far. Democratic leaders Nancy Pelosi and Steny Hoyer have strongly condemned the makeup of the committee — it has seven Republicans and five Dems, while Pelosi and Hoyer wanted an even split — but neither has said whether Dems should, or will, take the ultimate step of boycotting it.

Israel made the case that the lessons of the government shutdown fight — in which Republicans fared worse but both sides ended up getting tarred — suggested Dems should not participate, one person present said.

A second source recounted that Israel said the following:

“If this were a fair inquiry, the Republicans would’ve accepted our offer for balanced rules. Instead, it has become a Republican political strategy meant to raise money and excite their base.  The American people want us to be focused on creating middle class jobs, not jobs for lawyers investigating Democrats. Republicans have now totally crossed the line by exploiting and fundraising off of this tragedy and the loss of brave Americans.  We should have nothing to do with that.”

Asked for comment, a DCCC spokesperson confirmed the quote.

One person present described Israel’s advice as follows: “He thought, based on the lessons of the shutdown, in which to some extent Republicans and Democrats were painted with the same brush, that it was in our best interests not to participate.”

The person added Israel argued that if Dems participate, they will be “perceived as part of the problem,” because the story will be “Democrats and Republicans are fighting again on TV.” (Those are the words of the person present.)

“His point was that people are tired of hearing about this and realize it is a partisan witch hunt and that most people see it for what it is,” the source continued.

Dem Rep. James Clyburn has also called for a Dem boycott of the probe, arguing that participating in a panel with a stacked make-up is akin to “bringing a noose to my hanging.”

The case that people may see the Benghazi probe as a “partisan witch hunt” — and that for Republicans, this is more about galvanizing the base than anything else — may get a boost from the news that the head of the committee and the campaign arm for House Republicans disagree over whether this is a legitimate topic for fundraising.

GOP Rep. Trey Gowdy told MSNBC this morning that lawmakers should not raise money off Benghazi, noting that “even in a culture of hyper-partisanship,” some things “ought to be above politics, like the murder of our four fellow Americans.”

But the NRCC is raising money off the pending investigation. As Huffington Post and Politico report, the NRCC sent out an email that cites the Gowdy investigation, and links to a contribution page that gives folks the opportunity to become a “Benghazi watchdog,” asking for donations from between $25 and $200.

Notably, the NRCC’s fundraising graphic is very straightforward about the goals of the investigation, and appears to have already reached a conclusion about this whole affair. “Let’s go after Obama and Hillary Clinton,” it says. “Benghazi was a cover up.”

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.