Democrats Brian Higgins and Louise M. Slaughter are the big losers in a critical race where population means power.
No one else in the state's 29-member congressional delegation represents a district that lost so many residents in the past 10 years.
The overall decline in population in the region, documented in census figures released Thursday, all but assures that Western New York will lose one seat in Congress.
It also creates the possibility of pitting Higgins and Slaughter, both popular Democrats, against each other in next year's election.
A more likely prospect, some say, would involve splitting the district previously represented by Chris Lee, an Amherst Republican, between the Higgins and Slaughter districts.
"It's going to get personal and very political," said Robert Davis, former chairman of the Erie County Republican Party. "There's going to be some major wheeling and dealing going on."
Slaughter was the biggest loser, by far. Her 28th Congressional District, which stretches from Buffalo east to Rochester, lost 42,522 residents, more than any other district in the state.
Higgins' 27th Congressional District was second with a loss of 25,090.
The region's two other districts gained population. The 26th, previously represented by Lee, grew by 20,443, while the 29th, represented by Tom Reed, a Corning Republican, added 9,336 people.
No one would confirm that Western New York definitely will lose a seat, one of two to be relinquished statewide, but several lawmakers previously indicated that's a strong possibility.
"The numbers don't lie," said Assemblyman Robin Schimminger, a Kenmore Democrat. "It's just a matter of doing the math."
Redrawing congressional boundaries every 10 years tends to be a very partisan process, with incumbents in both parties fighting to maintain politically favorable districts.
The final decision on how it gets done rests with the State Legislature and Gov. Andrew M. Cuomo, although some lawmakers have endorsed establishing an independent, nonpartisan commission to handle the task.
But all four Western New York districts, even the two that gained population, are certain to change dramatically.
"No question about it," said State State Sen. George D. Maziarz, a Newfane Republican.
Each district will have to grow to meet the new population threshold -- 717,707, compared with the current 654,360 -- for each individual member of Congress. The increase stems from the rise in population nationwide.
"Even if they didn't lose population, there's going to be shifting, no doubt about it," said Assemblyman John J. McEneny, an Albany Democrat and a member of the Legislature's eight-person redistricting commission.
State lawmakers acknowledged the population decline in Western New York but said comment was premature on whether that means the loss of a seat here.
"There are no foregone conclusions," said State Sen. Michael F. Nozzolio, a Republican from Fayette in Seneca County. "It's far too early to speculate on where districts will be."
At least one congressional veteran says the loss of a seat here is likely, especially in light of the new, higher population threshold.
"I think it's highly probable," said former Rep. John J. LaFalce, a Town of Tonawanda Democrat. "If Brian Higgins needs 80,000 people and Louise Slaughter needs more than 100,000 people, where do they come from?"
Even though Slaughter and Higgins lost more people than any other member of the state's congressional delegation, that doesn't necessarily mean their seats would be at risk.
Historically, the state's redistricting effort has been rife with the kind of internal politics and behind-the-scenes lobbying that tends to benefit more-senior members.
If that holds true, the winner of the May 24 special election for the 26th Congressional District seat vacated by Lee may be more vulnerable than Higgins or Slaughter.
That race pits Assemblywoman Jane L. Corwin, a Republican, against Erie County Clerk Kathleen C. Hochul, a Democrat. Both would be first-year members of Congress.
"Who's going to have more juice, that's what's it going to come down to," Davis said.
In a statement Thursday, Slaughter noted that, in her 24 years in Congress, she has represented seven different counties.
"I have consistently said that a seat in Congress is a gift given to me by the people I'm proud to represent," the Fairport Democrat said. "I consider it a privilege."
Critics of the state's redistricting effort often point to Slaughter's earmuff-shaped district that links Buffalo with Rochester via a narrow strip of Lake Ontario shoreline -- as an example of the need to reform the redistricting process.
"I was aghast at the creation of an ear-muff district," said Schimminger, who supports the creation of an independent commission. "It defied all the rules."
He's not alone.
The New York Public Interest Research Group is pushing the idea and issued an analysis Thursday that suggests downstate, not upstate, would lose two seats under a nongerrymandered plan.
"In our ideal, the districts in Western New York would simply get pushed east toward the Hudson Valley," said Bill Mahoney, NYPIRG's research coordinator.
The shift, he said, would reflect the strong population growth in the Hudson Valley and the fact that upstate as a whole still has enough population to warrant keeping its current allotment of 10 congressional members.