ABC News’ Rick Klein reports: More than just a Senate seat is being decided today in Massachusetts — at stake is the Democratic Party’s 60-seat majority in the Senate, the future of health care reform, and, to some extent, the rest of President Obama’s agenda. We’ll be watching closely to see, among other things: – Do independents abandon the Democratic Party in a third straight statewide election, after last fall’s gubernatorial races in New Jersey and Virginia? – Will the grassroots enthusiasm for Republican Scott Brown translate into votes? – Can the old Obama campaign army still deliver on marching orders, in a heavily Democratic state? – Will Democrats nationwide get scared of what they see in Massachusetts? Would a loss by Democrat Martha Coakley cause a rush for the exits in advance of the mid-term congressional elections? – Is there a plausible Plan B on health care, should Democrats lose their 60th vote? (Suggestions today are that there might not be, as ABC’s Jake Tapper reports.) – How will President Obama respond to all of this? Would the president interpret a loss as a public rebuke — or use it as a call to arms for his supporters to get find some of their old enthusiasm? – If Coakley defies expectations and pull off a victory, does that give Democrats some newfound momentum? I chatted about what’s at stake in the race on “World News Now” this morning. Watch that HERE.