Brown, Casey, Menendez...

Democrats are now one-third of the way to claiming the Senate for the first time since 2001, with Sherrod Brown knocking off Mike DeWine in Ohio and Bob Casey, Jr. dethroning Pennsylvania'a Rick Santorum. Neither of these results are surprising -- Santorum has not led in a single public poll over the last 22 months, and national Republicans actually pulled resources out of DeWine's effort last month.

But the six-seat gain Democrats need to reclaim the majority is very much within sight right now. In New Jersey, Robert Menendez has held off Republican Tom Kean, preserving for the Democrats a seat that appeared to be in serious jeopardy last month, when news of a federal criminal probe of Menendez leaked from the U.S. Attorney's office.

All eyes are now on Virginia, Rhode Island, Missouri, Montana, Tennessee and Arizona. Win four of those, and Democrats have their majority-- assuming, of course, that they retain Maryland, where final results could take a few days.

-- Steve Kornacki