State Rep. Paul Hollis, a long-shot candidate for U.S. Senate who loaned himself more than $500,000, is dropping out of the race.

"After prayer and thoughtful consideration, I have decided to withdraw from the U.S. Senate race in Louisiana," the Republican said in a Monday statement. "I am thankful for the outpouring of support from voters throughout the state and truly appreciate the tireless efforts of our campaign's staff and volunteers."

Through March, Hollis, also a businessman, loaned his campaign about $556,000 and had more than $428,000 in his campaign account. But he struggled to gain traction against better-known competitors. Rep. Bill Cassidy is the clear Republican front-runner against Sen. Mary Landrieu (D). Also in the running: retired U.S. Air Force Col. Rob Maness (R).

All candidates running for Senate will compete in the same Nov. 4 primary. A runoff will take place in December if no candidate wins a majority.