Serious tea party-supported primary challengers to incumbent Republican Senators are a lot rarer this year than in 2010 -- pretty much the only one is in Indiana, where six-term Senator Dick Lugar is facing a spirited challenge from state Treasurer Richard Mourdock.
With the primary less than three weeks away, Mourdock has grabbed a narrow lead, 42-41, according to an internal poll from his campaign.
Well within the margin of error, but as the pollsters note, Mourdock clearly has "the momentum to win."
As with Sharron Angle and Christine O'Donnell two years ago, this would be good news for Democrats.
Mourdock has been the tea party/right-wing favorite from the start, supported by Tea Party Express, FreedomWorks, the Club for Growth, the NRA, and lots of in-state tea parties.
Unlike Angle and O'Donnell, he has been elected statewide, and has not said anything so stupid to attract national media attention.
Lugar has been handicapped by a Santorum-like residency issue, a lackluster performance in the only debate last week, and several bipartisan votes (like for Supreme Court Justices Kagan and Sotomayor) that are considered heretical by the tea party base.
Even before the debate, Lugar was not polling well -- a Howey/DePauw poll in early April found him ahead of Mourdock by 42-35 among all voters, but tied at 38 among Republican voters (Indiana has an open primary).
42 is not a good number for a well-known incumbent a month out, nor is the tie among the most motivated and likely voters in a Republican primary.
There is more Mourdock momentum in the first quarter fundraising reports -- he outraised Lugar $875K to $820K. Lugar has about $2M more cash-on-hand, but Mourdock has outside third parties helping a lot with TV attack ads.
This is all great news for the Democratic candidate -- Rep. Joe Donnelly, IN-2. In the same Howey/DePauw poll, he would lose to Lugar by 50-29, but is tied with Mourdock at 38.
Donnelly is no Elizabeth Warren, but this is Indiana, which has not elected a liberal Democrat to the Senate in almost 40 years. And more Democrats will be vitally important in this election, otherwise we lose the Senate.
Should Mourdock win the primary, we will have an excellent chance of an unexpected pick-up of a longtime Republican Senate seat.
And we should therefore be prepared to give Donnelly some substantial credit-card love, which he will surely need given the millions that the wingnut groups will spend on Mourdock's behalf.