Donald Trump surviving an attempted assassination makes him a martyr in the eyes of millions of Americans -- and shakes up the election too ... so says a presidential historian.
Douglas Brinkley -- a professor at Rice University and an expert in all things POTUS history -- tells TMZ ... the shooting gives Trump a chance to ride a wave of momentum to the White House, with DT emerging from the bloody rally looking like a leader and a brave warrior.
The image of a bloodied Trump pumping his fist is giving his campaign a shot in the arm, Douglas says ... and the shooting will likely be talked about and dissected all summer.
It's the first shooting of a current or former U.S. president since Ronald Reagan in 1981 ... and Douglas says the visuals may give Trump a boost with the TikTok generation, who are glued to their phones even more now.
While Douglas says the shooting swings momentum in Trump's favor for now -- he notes there's still a long way to go until November ... and he says the jury is still out on how much this affects the election when November rolls around.
BTW, DB says Biden still has a chance at a comeback ... noting Biden needs to heal the rift within the Democratic party first, use next month's DNC to get voters reengaged on kitchen table issues and shift the focus back on the strengths of his presidency if he wants a shot.
Bottom line for Douglas ... the shooting has Trump on offense and Biden on defense at the moment, but there's plenty of time for things to shift.
Stay tuned ...