Such a new party could only succeed if it drew heavily on moderate Democrats leaving the progressive liberals pretty isolated, while the core Republican party would remain relatively intact.
New parties tend to start at the Congressional House level. Seats tend to "flip" in moderate districts and typically moderate Republicans and moderate Democrats compete for those seats. More often than not those seats are in Democratic states with moderate suburban Republicans or Republican states with heavily Democratic urban areas. But where would these slightly conservative new House members align themselves if they were members of a new "moderate" party... with progressive liberals who want to radically change our country or with conservatives who want to tweak a few problems but leave the core unchanged?
Think about this past election... only by selling Biden as a moderate did he win. But what if a third party had siphoned off the moderate Democrat vote? More importantly, given how Biden has betrayed this group that believed him when he said he would push for bipartisanship if elected, I suspect things are going to turn out quite interesting in 2022. Obama pulled this stunt in 2008 and it backfired on him in 2010.
I think most liberals confuse Trump the person with Trump's policies. Trump's policies have fundamentally changed the Republican party to one whose heart and soul lie with working Americans, small business owners, and farmers. It message is appealing to workers of all all cultures and ethnicities as evidenced by the gains he made in 2020 among these groups.
The Democrats are a divided party comprised of the Bourbon Democrats, individuals who benefit or are dependent on income redistribution, government unions, and specific ethnic and racial identity groups largely concentrated in urban areas. Collectively, this is a large group (or a "big tent" as Democrats like to say) and It works when these groups can be rallied "against" something, but it tends to collapse when these groups are forced to be "for" something. Just as it is already showing cracks less than three weeks into Biden's Presidency... look at the simple issue of school re-openings and the conflict within the party between the unions and the parents...
