An effort involving several Republicans is afoot to get rapper Kanye West on the presidential ballot in key states. The idea is apparently that he might siphon some young and African American support from Joe Biden and help President Trump.

But a new poll provides a rare window into the limited appetite for third-party candidates in the 2020 election — and it appears to be a significant reason for Biden’s sustained advantage.

The Monmouth University poll is one of very few thus far this cycle that have included third-party candidates. And there’s a reason for that: The third-party candidates are relatively unknown and are apparently having little impact.

The poll shows Libertarian Party nominee Jo Jorgensen pulling 2 percent nationally, while Green Party nominee Howie Hawkins takes 1 percent. Previous polls from CNBC have also shown them in the low single digits.

That’s a marked contrast to where we were at this point four years ago. According to the RealClearPolitics average of polls back then, Libertarian nominee Gary Johnson was getting nearly 9 percent of the vote, while Green nominee Jill Stein was pulling about 4 percent.

Part of that was because of familiarity — both candidates were running for the second time in four years — but much of it owed to the unusual disillusionment with the two major-party nominees. Both Hillary Clinton and Donald Trump were viewed favorably by only about 4 in 10 voters. That left an apparently gaping hole for third-party candidates.

As is often the case, third-party support dropped as the election went on and voters coalesced around the two candidates who could win…