The Trump administration's tax reform bill is "fiscally irresponsible" and an assumption that growth will pay for the cuts is "delusional" — according to a top fixed income investment house.

"This is going to produce larger and larger deficits which will have to have to be made up at some point in the future," said Kapstream Capital Portfolio Manager Steve Goldman, who helps to oversee more than $11.8 billion dollars in funds under management.

The U.S. Senate approved a tax overhaul on Saturday, moving Republicans and President Donald Trump a step closer to their first major legislative win, and a goal to slash taxes to boost growth.

"In the short run, it looks like this is going to add somewhere between 0.2 and 0.3 percent to annualized growth, so it's a good short-run story," Goldman told CNBC's "The Rundown."

But the investor is less optimistic on the long-term benefits.

"Republicans have normally been known as the fiscally responsible party. This isn't something that you would call fiscally responsible," he said.