Keller: Diehl, Warren Should Be Satisfied With Their Debate Performance

BOSTON (CBS) - Going into their first U.S. Senate debate, Republican nominee and State Rep. Geoff Diehl faced a tall order – introduce himself in a positive way to the large percent of voters with no idea who he is while still going on offense against the Democrat Republicans love to hate, incumbent Sen. Elizabeth Warren.

For the most part, I'd say it was mission accomplished.

WATCH: Complete WBZ Senate Debate

In order to compete, Diehl had to excite and secure his base, the one million Massachusetts voters who backed Donald Trump in the 2016 presidential election. I suspect he did so by hammering Warren on her claims of Native American ancestry, her presidential ambitions, and zeroing in with passion on the hot button issues surrounding illegal immigration, especially when he recounted the horrific story of the murder of Weymouth police officer Michael Chesna last July.

But even if Diehl locks down every one of those 2016 Trump votes, he'll still need at least another half-million voters to swing his way to unseat Warren, including many socially-moderate but fiscally conservative Democrats and independents who've been willing to back Republicans here in the past. He tried hard, distancing himself from Senate Majority Leader Mitch McConnell, and finding common ground with Warren on some criminal justice reforms.

But his task was complicated by his opponent's zealous, relentless effort to tie the least popular politician in Massachusetts – President Trump – around Diehl's neck.

Warren hammered Diehl early on as a Trump lackey, and even linked him with Vice President Mike Pence at one point, both negatives for the Republican when it comes to reaching those swing voters. And Diehl stumbled a bit on Question 3, the effort to repeal certain LGBTQ rights in Massachusetts, a topic that brought a passionate response from Warren while Diehl was left to unconvincingly portray Trump as a defender of those rights.

And Warren was able at times to rebut what may be her biggest weakness – the perception that she and her Potomac fever have one foot out the door – by citing chapter and verse of her work on state issues, and promising to defend Massachusetts interests against – you guessed it – the Trump administration.

Both candidates have to be pleased by aspects of their performances Friday night, but was there a fundamental change in the trajectory of this race? I doubt it.