CLEVELAND – The Clinton campaign's all-out attack on Melania Trump for plagiarism won't work, and they should know – they tried it before. Against Barack Obama.

In the 2008 campaign, Clinton seized on revelations that Obama stole some memorable lines from Gov. Deval Patrick in an attempt to stop the Illinois senator.

"Lifting whole passages from someone's speeches isn't change you can believe in, it's change you can xerox," Clinton said in one debate.

This attack was so effective Obama promptly won the nomination. And who did he pick as vice president? Joe Biden, who has plagiarized so many times he's basically a serial offender.

So unless Clinton aides and their MSNBC sycophants want to admit that Obama and Biden's stealing makes them untrustworthy and unfit to hold office, they should lay off on Melania. Or at least make fake war hero Brian Williams leave the room when they're discussing it.

Yes, a few passages from Melania's prime-time speech were lifted from Michelle Obama. It was horrible timing. Trump's campaign should stop denying it and move on with the convention. Even many Trump loyalists aren't in denial.

But Obama didn't exactly own up when confronted about stealing basically word-for-word Patrick's powerful "just words" riff. He claimed it wasn't plagiarism because the Massachusetts governor "gave me the line and suggested I use it."

At the time, MSNBC's Chris Matthews lashed out at Clinton's campaign for trying to use the plagiarism charge against Obama, comparing it to the old political adage of "taking this little bitty thing and making it the biggest thing you ever saw."

"We know what they do, the people who work for Sen. Clinton, this is what they do," Matthews said indignantly.

Exactly, Chris.