WASHINGTON — The lawyer for White House Correspondence Dinner shooting suspect Cole Allen gave an absurd reason for why the CalTech grad should be allowed to walk free pending trial — despite charges that he attempted to assassinate President Trump.

Defense attorneys claimed that Allen, 31, was not prepared to carry out a mass shooting in the room where Trump, first lady Melania and most of the top members of the administration were in attendance — because he had a pump-action shotgun.

“Mr. Allen has no criminal history — not even prior arrests, which alone would rebut the presumption of detention,” they wrote in an 11-page filing on Thursday.

“The government’s rhetoric about a ‘mass shooting’ is also unsupported by its own proffered facts. Mr. Allen was not alleged to be holding an automatic or even semi-automatic weapon that are the hallmarks of the modern day mass shooting,” they added.

Allen was carrying a fully loaded 12-gauge Mossberg Maverick shotgun with an extended magazine tube when he tried to barge through a Secret Service checkpoint at the dinner, feds say.

Prosecutors also released a selfie he took showing him armed to the teeth — including with a .38 Super-caliber semi-automatic handgun and multiple knives.

Shotguns have been used in multiple mass shootings, including at Columbine, in the Aurora theater shooting in 2012 and the 2018 Santa Fe, Texas high school shooting.

However, during a brief hearing Thursday, defense attorney Tezira Abe reversed course saying, “At this time, we are conceding detention.”

Abe said the defense could still raise the issue of bail at a later date.

Allen’s lawyers also argued that he had no criminal history and previously had been a respected member of his community.

“He is a devout Christian who has spent countless hours with church groups for as long as family and friends can remember. He is a loved and respected teacher and colleague who has always demonstrated kindness, empathy and compassion and never violence,” wrote the federal public defenders.

They also disputed federal prosecutors’ claims that the WHCD shooting was intended to target the president, based on a manifesto the accused shooter sent out. In the note, first reported by The Post, Allen said he wanted to kill any member of the Trump administration he could — except FBI Director Kash Patel.

“The government’s evidence of the charged offense – the attempted assassination of the president – is thus built entirely upon speculation, even under the most generous reading of its theory,” they concluded.

“While the government may be able to say that the letter expresses an intent to target administration officials, it falls well short of narrowing those officials to President Trump.”

Prosecutors have argued for his detention before heading to trial on charges of attempting to assassinate Trump, traveling across state lines with a firearm to commit a felony and discharging a firearm during a crime of violence.

Photos released in court papers on Thursday by the prosecution showed Allen taking a chilling selfie in the mirror of his room at the Washington Hilton — before heading down and attempting to breach a security checkpoint.