WASHINGTON — Want to know what a lot of Republicans have been thinking about in the days leading up to Donald Trump’s first State of the Union address to a Republican-controlled Congress?

A new party.

At think-tank conference tables, over coffee at the Senate Chef and at the incessant book parties on the Washington social circuit, disaffected Republicans are wondering whether, if they came up with a truly great candidate, they could jump-start a new party, just as the original Republicans did in the 1850s.

And if surveys have any truth to them, plenty of Americans are ready to join them. A September Gallup poll found 61 percent of American voters support the idea of a third major political party, the highest level of support Gallup had ever recorded. Young voters seem especially eager to junk the two-party system; NBC reported in November that 71 percent of millennials want another choice.

In a world in which Alabama voters elected a Democratic senator, all kinds of previously unimaginable possibilities make a new kind of sense. A third-party presidency in 2020 is no less likely today than the prospect of Donald Trump’s election appeared to be two years ago.