Fine Gael TD Olivia Mitchell has described the changes to constituency boundaries as a "butchering".
Deputy Mitchell made the comments following the publication of the Constituency Commission report which has recommended a cut in the number of TDs from 166 to 158.
It also calls for a reduction in the number of constituencies through mergers and changes to boundaries.
That means significant changes to most parts of the country with only eight constituencies remaining unaffected.
Deputy Mitchell is in the constituency of Dublin South, which has lost two seats and been renamed as Dublin Rathdown.
She said the changes are a real challenge.
"It's a butchering certainly, and it's going to be a challenge for sitting TDs I think," she said.
"It's always harder to get elected in a three-seater because of course you need to get a quarter of the vote as opposed to a sixth to get a quota".
"So it's definitely going to be a challenge," she added.
Meanwhile Fianna Fáil TD Willie O'Dea, whose Limerick City constituency has had some boundary changes recommended, is pleased with the report.
He said he has suffered in past revisions and simply had to adjust.
"In the last revision, I lost up to 4,000 votes - now we're getting some of them back," he said.
"I just had to adjust myself to the new reality and work much harder in the new constituency; but thankfully with the support of the people of Limerick city I survived," he added.
Read more: Constituency Commission recommends cutting number of TDs by eight