While 99.9% of liberals and most independents think the Tea Party is just an extreme far right wing faction of the Republican Party, in reality they are stronger than that. The Tea Party candidates won't fare well in a general election but in a Republican Primary I'd never count them out.
To be hones, I do think there is a strong chance Brat will in fact defeat Majority Leader Cantor. For one, Cantor has already lost a recent election, which had a strong effect on the future events of elections. I feel Brad now has a decent shot in defeating him.
Yes, tea party challenger Brad will defeat Majority Leader Cantor, because people are sick of the Republicans having top-down leadership. They tell the rest of us what to do. It is time for the Republican leadership to start doing what their constituents want them to do. Cantor lost because he does not respond to his people.
The great thing about the Tea Party is no one cares. We have a enough sense to know that the primaries aren't particularly important and in the end we'll be left with two equally bad candidates. The Tea Party has been blocked on many fronts and even though they continue to plod forward, it doesn't mean they're making head way.