The Trump-Mueller clash is intensifying as primary voters head to the polls in key races that will ultimately shape the balance of power in Congress. Candidates seeking the Republican nomination next week for U.S. Senate seats in West Virginia and Indiana, for example, have been echoing Trump’s “witch hunt” rhetoric. And party strategists say base voters could be motivated not just through the primary season but into the general election by the continued investigation, which they perceive to have ventured beyond its mandate — and was possibly unwarranted in the first place.

“This is a battle between the forces of permanent Washington and the forces of voters outside of Washington,” said Dallas Woodhouse, the executive director of the Republican Party of North Carolina. “Voters see themselves in this fight with the president. … They do not like being told by the Democrats that they are gullible and stupid and manipulated by the Russians.”