Senate Republicans rejected a bill that would have limited President Trump’s ability to use military force against drug cartels, with the vote largely along party lines at 48-51.

The resolution would have required congressional approval for further strikes, which the White House justifies by labeling traffickers as armed combatants threatening the U.S.

So far, Trump’s campaign has destroyed four vessels, killed at least 21 people, and stopped narcotics from reaching America.

Republicans are seeking more details on the legal basis and conduct of the strikes, while Democrats argue they violate U.S. and international law, the Associated Press has reported.

Though the legislation failed, it allowed lawmakers to formally voice objections to the president’s assertion of war powers.