PostgreSQL: does the order of rows in a bulk insert control the order of `FOR EACH ROW` triggers?

I have a trigger like BEFORE INSERT ON table_a FOR EACH ROW EXECUTE FUNCTION upsert_into_table_b(). If I execute a bulk insert like INSERT INTO table_a ([columns]) VALUES ([row 1 values]), ([row 2 values])..., will the trigger run sequentially on the table_a rows in the order they were stated? In other words, will the upsert into table_b be done for row 1, then for row 2, in the order they were given in VALUES? (I ask because, if so, reordering the VALUES may help me solve a deadlock on the upsert.)