Three recent Trump tweets about Strange were deleted Tuesday night, according to ProPublica, which tracks deleted tweets.
This came shortly after Strange appeared headed for a loss, despite Trump's efforts to help the candidate.
The deleted tweets had touted Trump's personal endorsement of Strange.
On Tuesday morning, Trump had tweeted: "ALABAMA, get out and vote for Luther Strange - he has proven to me that he will never let you down! #MAGA"
Earlier in the morning, Trump had tweeted: "Luther Strange has been shooting up in the Alabama polls since my endorsement. Finish the job - vote today for 'Big Luther.'"
On Monday night, Trump had tweeted: "Big election tomorrow in the Great State of Alabama. Vote for Senator Luther Strange, tough on crime & border - will never let you down!"
Those three tweets were deleted Tuesday after Roy Moore appeared to have beaten Strange. Strange conceded shortly after 8:30 p.m. local time, 9:30 p.m. ET.
CNN reached out to the White House regarding the deleted tweets.
Trump's post congratulating Moore on Tuesday night, remained visible on his Twitter account.
That tweet read: "Congratulations to Roy Moore on his Republican Primary win in Alabama. Luther Strange started way back & ran a good race. Roy, WIN in Dec!"
Moore now faces Democratic nominee Doug Jones in a December general election in the race to replace Attorney General Jeff Sessions.
Trump's older tweets endorsing Strange, dating back to last week, remained public.
Trump often deletes tweets from his personal account
over spelling mistakes and then quickly tweets corrected versions. Deletion of tweets have raised questions about how presidents' social media should be handled and preserved.
The question has also been raised whether Trump is violating the Presidential Records Act of 1978, which requires all the president's records be preserved for eventual release to the public on a delayed basis long after the commander in chief leaves office.