The pool -- a consortium of American news organizations, mostly television networks -- took into account the competitiveness of the states in the presidential, Senate and governors races, as well as referendums, said ABC News Elections Director Daniel Merkle, a member of the committee that manages the consortium.
The omitted states are Alaska, Arkansas, Delaware, Georgia, Hawaii, Idaho, Kentucky, Louisiana, Nebraska, North Dakota, Oklahoma, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, West Virginia and Wyoming, as well as the District of Columbia.
Some precincts from these states will be included in a separate national exit survey -- the number of precincts sampled nationally has been increased to 350 from 300 in 2008 -- but information about voter age, race, sex, religious preference and other pertinent data in those 19 states will not be available, Merkle said.
The budget for the exit polls is about the same as four years ago, he said, but would have had to be significantly increased to provide the same coverage as in 2008.
The aim "is to still deliver a quality product in the most important states" in the face of mounting survey costs, Merkle told The Washington Post, which first reported the decision.
"We are simply shifting resources to get the best coverage we can -- beefing up the national sample, beefing up the telephone polls, beefing up the battleground states," he told The New York Times.
TV networks have used exit polls since 1992. They help news organizations declare winners before states have finished counting votes, as well as offer insights into voters.
All the excluded states are classified as either "solid Obama" or "solid Romney," the Post said.
But the excluded states include a "toss-up" U.S. Senate race in North Dakota between Democratic former state Attorney General Heidi Heitkamp and Republican Rep. Rick Berg.
Two other omitted states include contests in the "leaning" Democratic category in the U.S. Senate race in Hawaii and the governor's race in West Virginia.
With Texas excluded, the nation's second-most populous state will not have a statewide exit poll. Nor will No. 9 Georgia.
This is the first time the pool has cut the number of states it surveys in a presidential election year.
In the 2010 midterm election, it conducted exit polls in about half the states.