The arresting photo, which includes text that more than a million people have been killed by guns since Lennon was shot in 1980, has been retweeted more than 11,000 times since it was posted Wednesday.
A retweet by the account associated with President Obama forwarded it to his more than 28 million followers. Retweets aren't always endorsements in Twitter etiquette, but Ono's activism comes at a time when President Obama and Democrats' push for more gun control after the Sandy Hook tragedy seems to be struggling.
A proposed assault weapons ban was stripped from a bill headed to the Senate floor. And that bill, which would universalize background checks, doesn't have the bipartisan support many backers would like.
Related: Ono Tweets Lennon's Bloody Glasses