You can find out more about O'Malley's March on Google; but his compact discs are available at Amazon:

https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=O%27Malley%27s+March&rh=i%3Aaps%2Ck%3AO%27Malley%27s+March

Since he withdrew from the Democratic presidential primary, he has made appearances with his band (all sold out). Apart from having been a great mayor of Baltimore and an outstanding governor of Maryland, he is the leader of his own Celtic or Irish band. He plays a mean guitar and banjo, and he sings rather well. Lots of fun.

Here's a bit more:

http://www.baltimoresun.com/entertainment/music/midnight-sun-blog/bal-martin-omalley-omalleys-march-creative-alliance-march-2016-story.html