Lawmakers may be poised to repeal one of the most controversial parts of the Affordable Care Act -- the so-called “Cadillac tax” on high-cost insurance -- but Republicans seeking to replace it with a cap on the unlimited tax exclusion for employer-sponsored coverage are certain to face a wall of resistance from employer and union groups strongly opposed to the policy. Congress last year delayed implementation of the Cadillac tax until 2020, and repeal of the tax is expected to...