How he has come to believe that Dem/Libs are a minority is a strange path I'm sure, but he believes.

He's technically not wrong.

Democrats are a minority of the country. As are Republicans. Far more people self-identify as independents than either party - only about 25-30% of the population self-identify as Democrats. And recently, slightly more people self-identify as Republicans than Democrats:

news.gallup.com - Party affiliation

The same is true of Liberals - they are also a minority of the country. As are Conservatives, since about a third of Americans self-identify as moderates. Until very recently, there were also sizably more Conservatives than Liberals - they're more evenly split nowadays, but neither is a majority and a third or fewer of the country are liberals:

news.gallup.com - Increase liberal views brings ideological parity social issues

If we put that together and lump in the moderates as "leaners," we find that the "Dem/Lib" is slightly less than one-quarter of the country. A slight majority of Democrats (and leaners) identify as conservative/moderate, so only about 23% of Americans identify as both liberals and democrats. Republicans are more "purely" conservative, with most Republicans (and leaners) identifying as conservative and only a small number identifying as liberal/moderate. IOW, the liberal base of the Democratic party is smaller than the conservative base of the Republican party:

pewresearch.org - The partisanship and ideology of american voters