Democrat control of the U.S. Senate is in serious jeopardy this November. Of the 33 seats up for election this Fall, Democrats are defending 22. The GOP needs a net-gain of 4 seats to take control of the chamber (3 if Romney is elected, as the GOP VP would provide a tie-breaking vote.) Of the 8 seats considered "toss up" by RealClearPolitics, Democrats are defending six. Moreover, though, Democrats are defending 8 seats in Presidential battleground states, linking their fates to the Obama/Romney contest.In recent years, contested Senate races have tended to "break" in favor of one party. In 2006, Democrats picked up 6 seats and didn't lose any. In 2008, Dems picked up 8 and again successfully defended every seat. Same too for the GOP in 2010, who picked up 6 seats without losing any they had held. If the election contest breaks discernibly for either Obama or Romney, the Senate races in the 8 battleground states will likely break towards the candidate's party, delivering the Senate to the party of the Presidential victor.