Donald Trump's Son Eric Tweets Image of His Ballot, Illegally

— -- Eric Trump wanted to leave no doubt that he voted for his father, Republican presidential nominee Donald Trump.

So earlier this morning, Eric Trump tweeted a picture of his ballot, filled out with a vote for his father.

Along with the picture, Eric Trump tweeted, “It is an incredible honor to vote for my father! He will do such a great job for the U.S.A! #MakeAmericaGreatAgain.”

The only problem: It is illegal in the state of New York, where he voted, to take a picture of a completed ballot; doing so or showing how someone voted is a misdemeanor and is punishable by a $1,000 fine.

Trump was called out on Twitter by voter watchdog group Electionland, a collaboration of ProPublica and newsrooms across the country.

“A quick reminder to other New York voters: This is actually illegal. Please do not post a picture of your ballot (or a ballot selfie),” Electionland tweeted, with a link to Eric Trump’s tweet.

Eric Trump eventually deleted the tweet. But not before Electionland’s tweet was retweeted more than 900 times, the group reported.

Although 17 other states have similar laws prohibiting ballot selfies, the laws are rarely enforced. Justin Timberlake faced a similar issue while voting early in Tennessee this year, but the district attorney there said the matter would not be investigated.

Last week a federal judge in New York rejected a request from voters in Manhattan and Brooklyn to suspend the law to allow ballot selfies in the state. The judge said, “A last-minute, judicially imposed change in the protocol at 5,300 polling places would be a recipe for delays and a disorderly election.”

Ballot selfies are allowed in 20 states and the District of Columbia, according to The Associated Press. In the remaining 12 states, the laws are mixed or unclear.

ABC News’ Aaron Katersky contributed to this story.