McCartney, 72, said however his attempts have not gone as planned and he is not giving up on creating a protest anthem, reported Contactmusic.
"I was thinking recently about all these protests in New York and around the country. I thought it would be great to put something down about that, just to add my voice to the thousands of people walking in the streets.
"I'm not giving up on it, but it didn't come easily, whereas some other emotions might come easily to me," said McCartney.