EXCLUSIVE

Lindsay Lohan says she has a good reason for supporting a presidential candidate in Brazil ... she says her "Brazilian contacts" like the guy -- a guy whose company owned a chopper filled with tons of coke.

Lindsay tweeted, "I support @aecioNeves, for presidential candidature. His platform brings positive changes in Brazil."

Lindsay took a beating for getting involved in anyone's politics for obvious reasons. But a source connected with LiLo tells TMZ, she's supporting the guy because "she has plenty of contacts there and has several business trips to the country." The source also says she has a "good contact" in Brazil who likes Neves a lot.

Here's what Lindsay's 8.5 million followers need to know. Neves owns a company that owns a helicopter that was seized by the federal police ... seized because it was carrying 4.5 TONS of cocaine.