Spieth, 19, shot a 5-under-par 66 to finish 36 holes at 7-under 135, the same score posted by first-round leader Roberto Castro.
None of the afternoon starters were able to finish the second round before heavy rains forced a stoppage of play shortly before 3 p.m. EDT. The action never resumed and tournament officials hope to complete the second round early Saturday. Those who make the 36-hole cut will go off both the first and 10th tees when the third round gets underway.
Only three players in the tour's history have posted a victory prior to their 20th birthday and most recent to do so was Ralph Guldahl in 1931. Spieth will turn 20 next month.
Spieth left the University of Texas after his freshman season and tried to earn a spot on the tour at the qualifying tournament last year.
He failed at that attempt, but when he received a sponsor's exemption to play in the Puerto Rico Open in March he finished tied for second. That qualified him to play the next week at the Tampa Bay Championship and he wound up in a tie for seventh.
Spieth earned enough money from those two tournaments to qualify for as many sponsor's exemptions as he wanted this year and he has capitalized to post four Top 10 finishes -- one short of the best on the tour this season.
He is 39th on the money list and is guaranteed a spot on the tour for 2014. Spieth will become the seventh player in tour history to make it onto the circuit without going through the traditional qualifying process. Tiger Woods is one of those on that short list.
Spieth and Castro had a two-shot lead over D.H. Lee when play was suspended. Lee shot a 66 for a 5-under 137 total. Andres Romero was also at 5-under for the tournament with five holes to play.
Stewart Cink and rookie Russell Henley were among those at 139 in a tie for seventh place.