I am struggling to make a longtable fit on A4 pages in portrait mode. The problem is that the table is too wide. I am not allowed to use smaller fonts (that would solve my problem but it's not an option), and \tabcolsep nearly does it, but it shrinks the distance between columns globally and with my particular table I end up with columns that are almost overlapping each other, while there are several others where there still is plenty of space between them. If I could reduce the space just between those particular columns, the table would fit. Is there a way to do this without changing the spacing between ALL columns (since that would make the table unreadable, its content would overwrite itself)?