Can you explain what this "bold voice" has actually promised? Why - nothing! He literally promised to do nothing specific at all.

The Democrats being a center-right party, if you were a centrist, you'd be to the left of everyone.

The Democrats are to the right of the most popular right wing parties here in the Netherlands.

The test to see if a party is leftist is simple - do they believe that workers should control the means of production? Are they opposed to capitalism?

The Democrats are very pro-capitalism, and they go off on that theme over and over.

In the US, "centrist" means "I'm uneducated about politics entirely so I vote for people based on superficial and meaningless features."