Republican candidates on stage at the first GOP debate in Milwaukee, Wisconsin, on August 23, 2023.
CNN  — 

The candidates who will gather for the second Republican presidential debate this week face an unusual challenge: how to take on a front-runner who’s not on stage and is already acting as if he’s the nominee.

Former President Donald Trump’s posture was symbolized by his decision to hold a general election-style speech in Michigan rather than attend the debate.

Trump’s inclination to look past the primary, even before it’s officially begun, partially reflects the historic lead he has amassed in national polls. But it also derives from the failure of the other candidates to formulate a clear line of argument that might threaten him. That failure was on display during