Here motivated by the accepted answer, it might be useful to extend the function to remove both leading and trailing spaces.

Find What: ^\h+|\h+$|(\h+)
Replace With: (?{1}\t:)

• ^\h+ → Leading spaces (uncaptured).

• (\h+) → ​​Captures internal spaces​​ (Group 1).

• \h+$ → Trailing spaces (uncaptured).

If Group 1 (internal spaces) exists → Replace with \t (tab).

Else (leading/trailing spaces) → Replace with ​​nothing​​ (empty string).