For what kind of election?
For presidential elections - reach out to swing voters
For all other elections (midterms, primaries, off year elections, local elections) - fire up the base
For most groups, their share of the adult population and their share of the politically engaged is the same, or the % of politically engaged is lower than the share of the population. Except for the base of the 2 parties.
For core conservatives, they are 13% of adults. But 15% of registered voters and 20% of the politically engaged.
For solid liberals, they are 16% of adults. But 19% of registered voters and 25% of the politically engaged.
So for elections where turnout will be low, you want the base fired up because they are the ones that actually bother to vote. The other groups have lower turnout and are more likely to stay home in non-presidential year elections.
As a general rule of thumb, about 60-70 million people vote for each side of the isle in a presidential year national election, but only about 40 million for each side in a midterm.
Primaries and local elections are even worse. Only 30 million people voted in the democratic primary, despite Hillary winning 66 million votes in the general election. So about 36 million people who voted for her in the general stayed home and didn’t bother to vote in the democratic primary.
So basically, in a presidential year election focus on turnout which means appealing to centrists. For everything else, just fire up the base.
But again, centrists are followers. Not leaders. They aren’t thoughtful people. They are basically people who barely pay attention, they aren’t people who are highly politically engaged and are biding their time to figure out which politician reflects their core values. Just make sure they show up to vote in big elections because they barely bother to turn up unless it is a big election.