This has already become a wave election year, because a record wave of departures by House chairmen already guarantees a sea change in the Republican power structure next January.

Even if the GOP manages to hold on to its majority this fall, its policymaking muscle for the second half of President Donald Trump’s term will need some prolonged rehabilitation. And if the party gets swept back into the minority, its aptitude for stopping or co-opting the newly ascendant Democrats’ agenda will require some serious retraining.

That’s because more than a third of the Republicans who began this Congress with standing committee gavels in their hands, eight of the 21, will not be members of the House a year from now.

Neither will three GOP elders who had previously held prominent chairmanships — including California’s Darrell Issa, who gained national notoriety for his relentless grilling of Obama administration officials while running the Committee on Oversight and Government Reform, who announced his retirement Wednesday.

Watch: What’s Next for Seats of Retiring Chairmen?