That's scary stuff if you're a Democratic supporter, especially coming from an analyst whose accuracy made him a household name in the past few years. And the repeated name-dropping has probably opened some wallets for Senate Democrats.

"There's a lot of testing, particularly for subject lines, to see what has the best open rates," said Taryn Rosenkranz, a Democratic digital-fundraising consultant unaffiliated with the DSCC. "Using that name over and over suggests it's successful, and people are opening and giving."

The DSCC declined a request for comment.

Indeed, email fundraising is akin to a science in politics, in which campaigns and party committees test subject lines, messaging, layouts, the time that email is sent, the number of links, how many messages are sent—anything to increase the amount of money collected. Just a small percentage increase can lead to big money when soliciting a large list.

There are plenty of other themes in the past few months of DSCC emails, including alarming one-word subject lines such as "catastrophic," "disastrous," and "doomed." A few other individuals (besides Senate candidates) have been featured frequently, too. For example, one of the nonprofits affiliated with the conservative billionaire Koch brothers, Americans for Prosperity, has already spent about $30 million on advertising against Senate Democrats, and the Kochs appear prominently in email solicitations.

The DSCC has referenced the Kochs to shake money out of donors in no fewer than 77 fundraising emails in the past four months. But Silver has the conservative moneymen beat in one important metric. Only one DSCC email in that time features the Kochs in the subject line—perhaps the most critical part of the message because it must induce supporters to open the email before they can actually give money. Silver was cited far more often.

Silver rose to prominence by projecting the 2008 election results, and he then joined The New York Times, where he gained a bigger platform and enjoyed another successful year of political forecasting in 2012, correctly predicting the winner in all 50 states in the presidential election. He has since moved to ESPN, where he is relaunching FiveThirtyEight as a quantitative news site covering not only politics but also sports, economics, and other subjects.

Rosenkranz said she wasn't aware of any other Democratic campaigns or committees leveraging Silver's renown in the same way as the DSCC. But with Silver's new site launching on Monday, a new Senate forecast may be in the near future—and perhaps more emails, too.

"He's a trusted source of information," Rosenkranz said. "People don't have a lot of time to read email ... so you've got to capture their attention in some way."

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Scott Bland is the editor of National Journal's House Race Hotline. Connect Twitter