Rep. Thomas Massie, R-Ky., says he believes a majority of the public doubts the official U.S. government contention that Syrian President Bashar Assad used chemical gas against the final rebel-held town near Damascus.

“Anybody who has tried to explain to me why Assad would do this sounds like a conspiracy theorist,” said Massie, a libertarian Republican from Kentucky. “It requires really contorted thinking to think Assad did this. You have to come up with very complicated reasons.”

“I cannot think of a reason he would,” Massie said.

President Trump is openly weighing an attack on Syria’s government over the apparent April 7 chemical attack on Douma, tweeting Wednesday that missiles “will be coming” and referring to Assad as “a Gas Killing Animal who kills his people and enjoys it!”

The White House said Thursday afternoon that a final decision has not been made.

Massie told the Washington Examiner he believes “most of the public is thinking through it” and doesn't buy the official narrative blaming Assad for the deaths of about 40 people.

“I think less than 50 percent of the public is convinced Assad did this,” Massie said. “And what’s the threshold to convict someone in a murder trial? It has to be clear and convincing evidence before we start killing people over this. It can’t be, ‘He might have done this.’”

Massie said he believes Trump has not launched an attack yet because the U.S. government doesn’t have evidence to attribute the deaths to Assad, and fears an alternative explanation. He said it’s telling that members of Congress have not been offered a classified briefing.

Defense Secretary Jim Mattis said Thursday morning the U.S. still does not have evidence Assad launched a chemical attack on Douma. In February, Mattis admitted the U.S. has no evidence Assad used sarin gas in northern Idlib province in April 2017, an alleged chemical attack that prompted Trump to launch 59 Tomahawk missiles against a Syrian airbase.

Although many U.S. officials believe Assad is responsible for a chemical attack on Douma, Massie said he senses an undercurrent of doubt, though he lacks data to support his anecdotal observations.

“The general public seems to have more critical thinking than most members of Congress, and they are all still asking the question: Why would Assad attack his people with gas the same week of the announcement from our president that he’s going to pull out of Syria, knowing if a gas attack happened the president would likely retract his statement?” Massie said.

Massie said there are various possible explanations for the suspicious deaths in Douma, including an accident.

Although there’s precedent for Trump bombing Syria, there’s also precedent for backing down.

In 2013, President Barack Obama said he would bomb Assad’s government, before asking for a congressional vote when the U.K. parliament voted against joining the campaign. A release of chemical gas near Damascus had killed hundreds of people, and the attack was blamed on Assad. A subsequent United Nations investigation was unable to determine if Assad or rebels were responsible. Obama backed down when Russia said it would remove Syria’s chemical weapons.

A small but growing number of lawmakers are openly critical of a military strike against Assad. Massie's ideological ally, Rep. Justin Amash, R-Mich., said on Twitter an attack would be “unconstitutional & illegal” without a congressional vote or an attack on the U.S. or its troops. The top Democrat on the Senate Foreign Relations Committee, Sen. Bob Menendez, D-N.J., meanwhile, said Thursday Trump should get congressional authorization before an attack.

Skeptics of a military strike include Rep. John Duncan, R-Tenn., who gave a blistering statement Thursday on the House floor questioning the cost and wisdom of an intervention.

“We’ve had too many leaders who never went to war themselves, such as the new national security adviser John Bolton, who seem far too eager for others to go to war, so these chickenhawks can feel more important or think of themselves as a modern-day Winston Churchill,” Duncan said.

Massie said allegations of Assad's culpability should be seen in a broader historical context of government misattributions or lies.

“We were lied to about WMDs in Iraq," he said. "We had [former Director of National Intelligence James] Clapper admit he lied to Congress and a lot of the FBI folks have been reassigned or moved around."