... That's according to the Brookings Institution.

Brookings has taken to politically categorizing all House and Senate candidates running this year and keeping track of their wins and losses. Here's how the tea party looks so far:

Now, it should be emphasized that the tea party is supposed to be losing a lot more than it wins. That's because tea party groups often support the underdog against a well-established and well-funded (and often incumbent) opponent.

But before Dave Brat's win Tuesday and Sen. Thad Cochran's (R-Miss.) failure to avoid a runoff, it was looking like a pretty tough cycle for tea party candidates.

A better way to look at the tea party's fate is to look only at open primaries where the playing field is pretty even. But as Brookings showed last month, the tea party was winning less than one-third of such races -- which are really their best chance at influence in Congress: