Intense thunderstorms flooded the TPC-Louisiana course before most of the afternoon starters could begin play. Only 47 players finished the second round.
Tournament officials said play would resume at 7:30 a.m. Saturday.
Janzen, who has not won a PGA Tour event since capturing the second of his U.S. Open titles a dozen years ago, shot a 6-under 66 and stood at 7-under 137 for 36 holes. Brian Davis, who lost in a playoff at last week's Heritage, and Alex Cejka were also at 137.
Greg Owen was tied for the lead as well with one hole to play and first-round leader Jason Bohn, who shot a 7-under 65 on Thursday, had not started his round when the rains came.
Among those at 6-under were Greg Chalmers, who had finished his second round, and both Jarrold Lyle and David Duval. Lyle had completed 14 holes and Duval had played just four.
This is the 10th of 18 PGA Tour events this year to encounter some sort of stoppage due to weather. The forecast for Saturday is also not good, although officials still hope to be able to complete 72 holes by Sunday night.