harp on (?.)

• accent
• accentuate
• always trot out
• belabor
• dwell on
• dwell upon
• emphasize
• give emphasis to
• hammer away at
• highlight
• insist upon
• italicize
• labor
• overaccentuate
• overemphasize
• overstress
• place emphasis on
• point up
• punctuate
• rub in
• spotlight
• star
• stress
• thresh over
• underline
• underscore
• upon