Senate Republicans vulnerable to a Democratic challenge this year are facing a kind of political Catch-22 as the impeachment trial looms: Voting against President Trump risks the wrath of GOP primary voters, but voting for him ensures renomination but could cost them their careers in November.

Sens. Susan Collins of Maine, Cory Gardner of Colorado, and Martha McSally of Arizona are under the most pressure, and not just on whether to acquit or convict Trump on charges of abuse of power and obstruction of Congress. The Senate will vote on whether to call witnesses at trial, another political minefield.