Senate opponents of a treaty regulating the multibillion-dollar global arms trade said Wednesday they have the votes to block ratification of the pact, which is also opposed by the outlaw regimes of North Korea, Syria and Iran.

One day after the U.N. General Assembly overwhelmingly approved the treaty, Republican Sen. Mike Lee of Utah said it was “deeply flawed” and became the 35th senator to endorse a resolution of opposition. The Constitution requires two-thirds of the Senate — 67 votes — to ratify a treaty.

“I have great concerns that this treaty can be used to violate the second amendment rights of American citizens, and do not believe we should sign any treaty that infringes on the sovereignty of our country,” Lee said in a statement that reflected the strong objections of gun rights advocates.

The United States joined 153 nations in backing the treaty that proponents argue will keep weapons out of the hands of terrorists and human rights abusers. Iran, North Korea and Syria, which face international arms embargoes, voted against the pact.