Some are and some aren't. To claim all people in a given category of a political persuasion hold the same views on race is sort of limiting and needs further qualification.
For instance, if the political party was called "the Let's bomb the fuck out of the sneaky Japs even their women and children" party, it would be more likely those members were racists. That was the sentiment of many if not most of the racist Americans in the 1940s. I think that was aided by racist democrat Presidents FDR and Harry Truman and their actions.
To say ALL democrats these days are racist or ALL Republicans are racist is kind of a reach though. Racism exists now sure, but it's kind of an overworked thing to keep people fighting about it, so they are distracted from other things which are more ominous and prevalent.
Although, the democrat platform does seem to support some racist policies, like the well intended, but logically inept "affirmative action" type quota things.
If you support that, it might explain why YOU are a racist. I.E. judging a person on the color of their skin, rather than the content of their character.