I've heard differently.
Snowbarger did nothing to distinguish himself in his one term in Congress, didn't come back to the district a lot and was a terrible fund-raiser.
You could lay some blame on moderate Republicans who were still disgruntled over over the 1996 primary between Snowbarger and Ed Eilert - but to lay the blame entirely on moderate Republicans is not true.
A big factor in Snowbarger's defeat was the Clinton impeachment. There was a huge anti-conservative backlash among upscale white urban liberals in 1998.
All five Republican Congressmen defeated for reelection that year (Snowbarger, Rick White, Bill Redmond, Jon Fox, & Mike Pappas) represented districts with a significant number of such voters.