Rubio's repeated talking point was a tricky argument to begin with

Many voters, especially those already skeptical about Rubio, may hear him say “Obama knows exactly what he’s doing” over and over again and come away thinking he is pro-Obama.

Interestingly enough, Obama also found himself with a similar problem during the 2008 Democratic primary when he made the comment, “I think Ronald Reagan changed the trajectory of America in a way that, you know, Richard Nixon did not and in a way that Bill Clinton did not.” His argument was that Reagan was a transformative president who fundamentally altered the direction of the country, and he wanted to do for liberalism what Reagan did for conservatism.

But this fired up liberals and provided fuel to his opponents. Obama came under fire from both Hillary Clinton and John Edwards, who tried to portray him as failing to appreciate (from a liberal perspective) the awfulness of Reagan’s policies.