Idioms and Phrases with the thing is
the thing is
The issue, main point, or problem is, as in The thing is, we haven't enough money for the tickets. [Colloquial; late 1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.