Donald J. Trump is the presidential nominee of the Republican party. But that does not absolve every Republican office holder, donor, and activist from the responsibility of satisfying himself that it is right to support that nominee for president. There are, in my judgment, many reasons to doubt this is the case. But one reason in particular hasn’t received sufficient consideration: The fact that Trump and his top campaign aide have many troubling connections with Vladimir Putin’s regime.

Honest and patriotic Republicans who support Trump, or are tempted to do so, should review some of the publicly available evidence. Trump’s business seems to be heavily dependent on Russian investment. His top campaign advisor, Paul Manafort, was the advisor to the Putin-backed stooge Viktor Yanukovich, and has deep ties to the Putin apparat. One of Trump’s national security advisors, retired Lt. General Michael Flynn, was paid to give a speech at a Russian propaganda celebration and was seated next to Putin. Trump’s Russia advisor Carter Page, who does much of his business with Russian companies, has argued, among other things, that “a few officials in Washington” annexed Ukraine and that the “so-called annexation” of Crimea by Russia was a rational response to this injustice.