This one colossal cottontail!

Meet Jeff, a heavyweight hare from the UK who is poised to capture the title as world’s biggest bunny — from his also immense dad, Darius.

The papa rabbit is more than 4 feet long and 49 pounds — but Jeff is not far behind, at 3-foot-8 — and still has six months to reach full adult weight.

Annette Edwards, 63, of Bromsgrove, England, said she can’t wait for Jeff to capture the crown, even though it costs about $7,500 a year for carrots and apples to keep him growing.

As soon as Jeff tips the scales at the record weight, experts from Guinness will be called in to make it official, she said.