US Senate Republicans blocked a resolution on Thursday that would have prevented President Donald Trump from attacking Venezuela without congressional authorization, a day after administration officials told lawmakers that Washington is not currently planning strikes on Venezuelan territory.

The Senate voted 51 to 49, largely along party lines, against a measure that would have brought the war powers resolution up for a vote.

Only two of Trump’s fellow Republicans joined Democrats in backing the measure, in a show of the party’s support for Trump’s military buildup in the southern Caribbean after two months of deadly strikes against boats off Venezuela.

The Trump administration says that, since early September, US forces have launched at least 16 strikes against such vessels in the Pacific and southern Caribbean, killing more than 65 people.

The prolonged campaign has heightened concern that Trump will launch an attack on Venezuela itself, which prompted the introduction of the bipartisan resolution. Its lead sponsors were Democrats Tim Kaine of Virginia and Adam Schiff of California, and Republican Senator Rand Paul of Kentucky.

Trump has dangled the possibility of land attacks on Venezuela for weeks, saying at one point that he had authorized the Central Intelligence Agency to conduct covert operations in the country.

He later denied he was considering strikes inside Venezuela, even as Washington continued to build up a large military presence in the Caribbean with fighter jets, warships and thousands of troops.

Secretary of State Marco Rubio and Secretary of Defence Pete Hegseth briefed congressional leaders and the Republican chairs and top Democrats on national security committees on the issue on Wednesday.

“Based on that briefing, I think the administration does not want to go to war with Venezuela,” Adam Smith of Washington, the ranking Democrat on the House of Representatives Armed Services Committee, told the Atlantic Council.

“But then again, President Trump is rather known for his - what would be the best way to put this - chaotic approach to things. He’s one to change his mind very quickly. So who knows?”

National security

Senator Mark Warner of Virginia, the top intelligence committee Democrat, said the legal justification for the boat strikes laid out by administration officials did not include justification for direct attacks on Venezuelan territory.

“Nothing in the legal opinion even mentions Venezuela,” Warner told reporters as he left Wednesday’s briefing.

A senior administration official said attacks against land targets would be justified on national security grounds.

Some legal experts say the strikes may violate international law as well as US laws against murder and prohibitions on assassination.

Members of Congress from both parties had complained they have received scant information, such as who was killed, evidence of drug trafficking, the buildup’s cost or the administration’s long-term Latin American strategy.

During debate on the resolution on Thursday, Senate Democratic leader Chuck Schumer of New York called on the Trump administration to hold a briefing for all 100 senators. Democrats have also called for a meeting with the full House of Representatives.

The administration has said those targeted were “narco-terrorists” transporting drugs that endangered Americans, without providing evidence or publicly explaining the legal justification for attacking the boats rather than stopping them and arresting those on board.

The US Constitution requires any president to obtain Congress’ approval before launching a prolonged military operation.

“The time is right for Congress to step in and reassert our congressional responsibility,” Schiff told a news conference before Thursday’s vote.

Opposing the resolution, Senator Jim Risch of Idaho, the Republican chairman of the Senate Foreign Relations Committee, said Trump had the authority he needed, as commander-in-chief. “I wish my colleagues would join me today in congratulating the president for what he has done,” he said.

It was only the latest attempt to rein in Trump’s war powers. The Senate blocked a resolution last month, by a vote of 51-48, that sought to stop the boat strikes. That vote was also mostly along party lines with the same two Republicans - Paul and Lisa Murkowski of Alaska - backing the measure.

Kaine and Schiff told reporters on Thursday they would consider options for trying another resolution after the vote.