Keller: After Heated Debate, Markey-Kennedy Race Still A Toss-Up

BOSTON (CBS) - If you love yourself some Joe Kennedy, Tuesday night's WBZ-TV debate left you satisfied. Kennedy took it to Ed Markey from the beginning, hammering home his core critique of the incumbent - that he doesn't have the energy, work ethic and vision to make sweeping changes needed in health care, the economy, and the treatment of people of color.

If it's Markey you prefer, you also left the table feeling full. He was sharper and more aggressive than in some of the previous debates, and seemed to stun Kennedy with his insistence that the congressman tell his brother and father, former Congressman Joe Kennedy II, to stop funding Super PAC attack ads that have been going after Markey's voting record.

So who won? That depends entirely on who the undecided voters in this apparent toss-up of a race are, and what they want.

WATCH: Complete U.S. Senate Debate

It is Kennedy's calculation, fueled by the trouncing Ayanna Pressley laid on longtime Congressman Mike Capuano in 2018, that her slogan - "Change Can't Wait" - reflects the current mood of swing voters. Whatever else one might say about Markey, there is no obvious reason, like a scandal of some kind, to dump him. But the same was true of Capuano. With the economic, social and public health status quo in ruins, the moment would seem ripe for an anti-incumbent backlash.

But while Kennedy has assiduously tried to paint Markey as a tired insider who simply doesn't "show up" to listen to and help his constituents the way he should, it's clear plenty of voters disagree, enough to make this a tight race. Swing voters might want change, but Markey effectively made the case Tuesday night that he's been a change agent and continues to be, his alliance on the Green New Deal with Rep Alexandria Ocasio-Cortez being exhibit A.

With his attack on Kennedy's family, Markey doubled down on a key strategic assumption - that the number of voters offended by the notion that the son of a famous, wealthy family would try to take out a longtime, reasonably-well-liked incumbent is greater than those who think well of the Kennedys. And after Tuesday night, he has to hope that the margin those attacks might provide will exceed the number of voters disturbed by police violence who may have gagged on Markey's contention that signing a couple of letters was evidence that he really did try his best to help the family of slain black Easton college student DJ Henry find justice, despite the family's claim he gave them short shrift.

The bottom line: this race remains impossible to decipher. No wagering is advised.