Actually, I can't believe I didn't think of this scenario...
National Popular Vote Compact. Mostly blue and purple states.
Republican wins the popular vote, so the red states (nonparticipants) are red. The blue states vote for the national popular vote winner so they're red as well.
The Compact would not necessarily rule out faithless electors, though. In fact, one commentator thinks it is constitutional precisely because it does not rule out faithless electors!
"For purposes of a Compact Clause analysis, the determination of
the electors’ roles is crucial, particularly when considering the NPVC
from an ex ante perspective. When viewed ex post, the NPVC looks
unconstitutional, as the exact effect contemplated by those who argue
against the NPVC does, in fact, occur. That is, pledged delegates vote
for the winner of the national popular vote, the winner of that vote
becomes president, and the non-signatory states will have had no say
in deciding how the president should be determined.249 However, when
viewed ex ante, the NPVC’s text appears to be doing something far different,
as it has no binding mechanism on the actual electors, but only
on the state legislatures.250 In the New Jersey Assembly Appropriations
Committee’s Statement that follows that state’s version of the NPVC,
the legislature presumes that the bill “requires” electors from signatory
states to vote for the national popular vote winner.251 However,
the bill’s text itself does not provide for any penalties if electors choose
to vote differently.252 Any binding mechanism on the actual electors
comes from the state enforcement statutes, and likely would survive
federal preemption.253
"As the
Ray Court made clear, neither the Constitution nor any federal
statute mandates that the electors vote for the candidate whom
they are pledged for.254 Only custom has made such the practice.255
Thus, under an ex ante framing of the NPVC, the agreement to allocate
electors in a uniform manner only gives the signatory states a
chance
to control the Electoral College, not a definitive guarantee that they
will control it.256 However, if all the signatory states subsequently adopt
criminal penalties or other statutes that bind the electors, then the ex
ante perspective might not have as much bite.257 While the NPVC as a
whole might be ripe for a court to evaluate prior to an election,258 the
constitutionality of a pledged delegate’s lack of adherence to the NPVC
and/or state enforcement statutes might present different questions
either independent of the NPVC or determinative of the NPVC’s
constitutionality.259..."
https://digitalcommons.wcl.american...eferer=&httpsredir=1&article=1043&context=lpb