Thousands of members of an influential religious group started gathering in Manila on Sunday for a rally to call for accountability in the Philippine government over a widening corruption scandal.

Iglesia ni Cristo members, wearing white shirts, assembled in the historic Quirino Grandstand and nearby streets in the city of Manila. Police estimated the crowd at 14,500 as of 8 a.m. local time. Some camped out overnight for a program expected to start late in the afternoon.

The Christian religious group earlier said it’s not fighting the government, and that it’s a peaceful movement against corruption. The megachurch holds political clout as it’s known for endorsing candidates and voting as a bloc during elections.