A United Nations treaty governing the open seas is expected to die in the Senate after two more Republicans announced their opposition.
The Law of the Sea Treaty establishes international regulations for maritime rights of countries.
Sen. Jim DeMint, R-S.C., and other conservatives have led the campaign against the treaty, saying it would undermine U.S. sovereignty.
DeMint tweeted Wednesday that, "34 Senators now oppose LOST, sinking the misguided treaty."
The treaty was introduced in 1994 and is signed and ratified by 162 countries. The United States signed the treaty, but never ratified it.
Ratification requires a two-thirds vote of the Senate, which equates to 67 votes in favor.
The Law of the Sea Treaty sets terms for resolving disputes in international waters and recognizes sovereign rights out to 200 nautical miles from a country's continental shelf.
The treaty has been endorsed by the Clinton, Bush, and Obama administrations.