Twitter finally lit up on Monday.  

Melania Trump is running for nothing. But still, her speech at the Republican convention in Cleveland included two passages that contained words and thoughts very similar to those from a 2008 speech delivered by Michelle Obama.  

The episode cast a new shadow over a presidential campaign that has had many unusual moments, to say the least.  

But plagiarism in the political arena is nothing new. Candidates have been suspected of or have admitted to borrowing from others to make their own points.  

Here are a few:  

Donald Trump rival Ben Carson was accused of plagiarism after his 2012 book, “America the Beautiful,” came out. Buzzfeed reported that he’d plagiarized SocialismSucks.net “and many other sources.”  

Former Democratic Sen. John Walsh of Montana, a retired Army general, was accused of including large chunks of material from other sources in a U.S. Army War College thesis, according to the New York Times.  

President Barack Obama was accused in 2008 of borrowing phraseology  from Deval Patrick, then the governor of Massachusetts. Obama said Patrick “gave him” the information, according to The New Yorker.  

In 2013, Sen. Rand Paul was accused of lifting material  from Wikipedia when talking publicly about the movie “Gattaca,” according to The Washington Post.  

Then, here’s the big one.  

In 1987, Sen. Joseph R. Biden Jr. dropped out of the 1988 presidential race over a plagiarism scandal involving a speech by Neil Kinnock, then the leader of the Labour Party leader in the U.K., the Post reported.