Matt Warman, MP for Boston and Skegness, said he had spoken to public health minister Jo Churchill about the two districts’ coronavirus infection rates on Tuesday night.
As of November 23, East Lindsey was the area with the third highest infection rates across the whole of the UK, with 515.8 against an England average of 239.9. Boston was 21st with 428.9, and Lincoln was also in the top 50 with 379.7.
In a post on Facebook, Mr Warman said: “We are the highest and 4th-highest parts of the whole East Midlands, and a cause of real concern for the minister.
“I’m hugely grateful for her personal attention, but the reality is that the area is highly likely to be put into tier three when the nationwide lockdown ends.”
The highest tiers’ rules include a total closure of hospitality venues except for takeaways, a limit to just one household indoors, and care homes closed to visitors.
Tier three areas may also be subject to a new mass testing pilot for six weeks.
Mr Warman said the reasons for the high infection rates included more widespread community transmission, a number of care home and factory outbreaks, and a lack of adherence to the rules.
He urged residents to follow the rules “so that we can get through to a sensible Christmas and ultimately towards a vaccine”.
Health bosses both nationally and locally won’t know officially where regions will land until the announcement is made on Thursday.
It is unclear if Lincolnshire will be tiered as a county under the new rules, or as separate districts.
Lincolnshire was in the lowest tier, and managed to escape moving into tier two before the national restrictions kicked in.
North Lincolnshire and North East Lincolnshire were both in tier two, and were quickly edging up towards tier three.
The two northern unitary authorities had infection rates of 448.1 each on Monday.