Knowing the prevailing mindset here, and the prevailing mindset among conservatives that I know, I just think the opposing party is dead to these people. I don’t think there is anything that can be said or done to convince them otherwise. These people see an R or D and their decision is effectively made, and little else matters.
I think Talarico’s message would need to come from an independent, or perhaps a new party founded by people who are eschewing both parties. If he could find a like mind from the Republican Party and get some monied people behind them, start a new party focused on de-escalation, unity, preserving the Republic and populist economics. That might pull a decent number of people from both parties that currently have been essentially forced to choose between two warring factions.
The problem when people make their decision between R or D right now, they fall into an information bubble provided by that side that has more to do with motivating them to join the fight than it has with promoting any sort of common ground. You are presented with the best of “your” side and the worst of the “other” side. And outside forces (Russia, others) contribute their weight to ensuring that half the people view the other half as a mortal threat and vice versa.
I fully know one or both parties would be trying to undermine these efforts of a new, upstart party and it very well might fail. But the alternative is a continuation of current trends, which likely means the extinction of the Democratic Party and 20th century liberalism. It might mean worse than that.